Uniformed Regular Verbal Conjugation of Japanese

In this article, I introduce "Uniformed Regular Verbal Conjugation of Japanese". This rule intend to regulate most of Japanese verbs. After knowing this rule, All Japanese learners and Japanese teachers can easily understand Japanese verbal conjugation. At present, Japanese traditional grammarians classify Japanese verbs as follows.

Five Vowels Regular Conjugation (五段正格活用)
Vowel I Regular Conjugation (上一段正格活用)
Vowel E Regular Conjugation (下一段正格活用)
Consonant K Irregular Conjugation (カ行変格活用)
Consonant S Irregular Conjugation (サ行変格活用)

However, under this classification, we have three separate regular conjugations. This might be certainly regular for a native speaker of Japanese but a Japanese learner is bothered by these three conjugations, whenever he / she memorizes new verbal words. He or she will be confused to choose a proper type.

Some Japanese teachers have made efforts to solve this problem. They have classified conjugations as follows after they identified Vowel I & E conjugations.

U Dropping Regular Conjugation (五段正格活用)
RU Dropping Regular Conjugation (一段正格活用)
Irregular Conjugation (不規則活用)
- Consonant K Irregular Conjugation (カ行変格活用)
- Consonant S Irregular Conjugation (サ行変格活用)

In above list. U Dropping one is identified with Five Vowels one. RU Dropping one is identified with the set of Vowel I and E one. However, there still remain two regular conjugations. Those teachers have also made good efforts to distinguish those two conjugations as follows.

U Dropping Verbs have the following phonemes at the ends.
- "KU", "SU", "TU", "NU", "MU", "ARU", "URU", "ORU", a vowel + "U", "GU", "BU".
RU Dropping Verbs have the following phonemes at the ends.
- "IRU", "ERU"

An exception still appears at the end of "IRU", "ERU". So some verbs like "KIRU"(cut), "KERU"(kick) are classified into U Dropping, though they have the end of "IRU", "ERU". However, this method is quite good since I had checked the number of such a kind of verbs before. The result is remarkable so that I have found about 50 verbs applied to this exception. This number is quite a few even if it is compared with the number of English irregular verbs. So I want to call these verbs as semi regular verbs According to my classifications, All of Japanese verbs are classified as the following 2 main categories and 5 sub categories.

Uniformed Regular Conjugation (統一規則活用)
- Dominant Stem (優性語幹)
- Recessive Stem (劣性語幹)
- Irregular Inflection (不規則語尾)
Irregular Conjugation (不規則活用)
- Consonant K Irregular Conjugation (カ行変格活用)
- Consonant S Irregular Conjugation (サ行変格活用)

Rule

Note

This rule is a kind of abbreviation. It does not have any historical and academic backgrounds. However, it is very helpful for a Japanese learner to understand Japanese regular verbs. If you would like to use this rule in your Japanese classroom, could you please introduce my web page to your students?

Basic Stem

Basic Stems
Japanese	basic stem	English
karu	kar	to cut
katu	kat	to win
kau	kaw	to buy
kesu	kes	to put out
sinu	sin	to die
tugu	tug	to succeed
tuku	tuk	to stick
tukeru	tuke	to attach
tukiru	tuki	to run out
yobu	yob	to call
yomu	yom	to read

Verbs of Uniformed Regular Conjugation have a basic stem. It is easy to find a basic stem by applying the following rules to their dictionary forms.

The verbs that have the end of "ERU" have the basic stem by dropping the end of "RU"
The other verbs have the basic stem by dropping the end of "U".
The verbs that have the end of a vowel + "U" have to add "W" consonants to their end of the basic stem.
Check the list of recessive stems type "I". 42 words are listed.
Check the list of recessive stems type "ER". 23 words are listed.

I pick up the examples in the following tables.

Inflections

Combining Formulas

Regulations

Inflections
inflection	function	Japanese	note
-anai	negative	打消	-azu is another negative inflection.
-eyo	imperative	命令	This inflection has many variants.
-i	adverbial	連用	It is followed by -masu, -tai, etc.
-rareru	passive	受身
-reba	conditional	仮定
-reru	possible	可能	It is not a standard but used commonly.
-ru	adjectival	連体	It is also used as a final inflection.
-saseru	causative	使役
-ta	perfect	完了	It is normally used as "ta" and "te".
-you	intention	意思

Combining Formulas
formula	condition	result
[F1] double vowels	a vowel followed by a vowel between a stem and am inflection	drop the vowel of top of an inflection
[F2] double consonants	a consonant followed by a consonant between a stem and an inflection	drop the consonant of top of an inflection
[F3] perfect inflection	a consonant followed by the perfect inflection "ita" between a stem and an inflection	kt changed into it
gt changed into id
st changed into sit
tt,rt,wt changed into tt
nt,mt,bt changed into nd

The following tables show us the practical conjugations of each stems. The first column tagged with "raw" means the raw conjugation adding inflections, and the second column tagged with "formula" means the combining formula used to create the practical form. The third column tagged with "practical" means the practical form used in a real life.

Regular Conjugations
		Vowel Ending Stem			Consonant Ending Stem
		tukeru (tuke-)			tuku (tuk-)
function	inflection	raw	formula	practical	raw	formula	practical
negative	-anai	tuke + anai	[F1]	tukenai	tuk + anai		tukanai
adverbial	-i	tuke + i	[F1]	tuke	tuk + i		tukaki
causative	-saseru	tuke + saseru		tukesaseru	tuk + saseru	[F2]	tukaseru
passive	-rareru	tuke + rareru		tukerareru	tuk + rarera	[F2]	tukareru
conditional	-reba	tuke + reba		tukereba	tuk + reba	[F2]	tukeba
adjectival	-ru	tuke + ru		tukeru	tuk + ru	[F2]	tuku
perfect	-ta	tuke + ta		tuketa	tuk + ta	[F3]	tuita
intention	-you	tuke + you		tukeyou	tuk + you	[F2]	tukou

The following table shows us the special rule applied to the perfect inflections.

Regular Conjugations of Perfect Inflection following Consonant Ending Stems
basic stem	raw	formula	practical	note
kar	kar + ta	[F3]	katta	voiceless	r,t,w changed into t	rt → (rt) → tt
kat	kat + ta	[F3]	katta			tt → (tt) → tt
kaw	kaw + ta	[F3]	katta			wt → (wt) → tt
kes	kes + ta	[F3]	kesita	voiceless	s chagened into si	st → (st) → sit
sin	sin + ta	[F3]	sinda	voiced	b,m,n changed into n	nt → (nd) → nd
yob	yob + ta	[F3]	yonda			bt → (bd) → nd
yom	yom + ta	[F3]	yonda			mt → (md) → nd
tug	tug + ta	[F3]	tuida	voiced	changed into i	gt → (gd) → id
tuk	tuk + ta	[F3]	tuita	voiceless	changed into i	kt → (kt) → it

If you know the practical examples more, please go to the appendixes.

The Lists of Recessive Stems

These lists shows us recessive stems. The recessive stems have regular conjugation. There is no problem to conjugate them with this characteristics. However, their form is so confusing as not to decide which part is a real stem, because there is no logical rule to divide a consonant ending stem form a vowel ending stem.

Recessive Stems Type -I (42 words)
	Japanese	basic stem	English
-I	iru	i	to be
	iru	i	to shoot
	iru	i	to coin
	oiru	oi	to age
	kuiru	kui	to regret
	siiru	sii	to force
	hikiiru	hikii	to lead
	mukuiru	mukui	to reward
	motiiru	motii	to use
-KI	kiru	ki	to ware
	akiru	aki	to get tired
	ikiru	iki	to live
	okiru	oki	to happen
	tukiru	tuki	to run out
-TI	otiru	oti	to drop
	kutiru	kuti	to rot
	mitiru	miti	to be full
-NI(*1)	niru	ni	to resemble
-NI(*1)	niru	ni	to boil
-HI(*1)	hiru	hi	to dry
-MI(*1)	miru	mi	to see
	simiru	simi	to pierce
	simiru	simi	to freeze
	kangamiru	kangami	to heed
-RI(*1)	oriru	ori	to descend
	kariru	kari	to rent
	koriru	kori	to be disgusted
	tariru	tari	to be enough
-GI	sugiru	sugi	to pass
-ZI	toziru	tozi	to feel ashamed
-ZI	haziru	hazi	to close
-BI(*1)	abiru	abi	to bathe
	obiru	obi	to ware
	kobiru	kobi	to flatter
	sabiru	sabi	to rust
	nobiru	nobi	to stretch
	wabiru	wabi	to apologize
	sinabiru	sinabi	to wilt
	hurubiru	hurubi	to look old
	horobiru	horobi	to be ruined
	hikarabiru	hikarabi	to dry up
	hokorobiru	hokorobi	to begin to open

Recessive Stems Type -ER (23 words)
	Japanese	basic stem	English
-ER	kaeru	kaer	to return
	kutugaeru	kutugaer	to be overturned
	hirugaeru	hirugaer	to turn over
	yomigaeru	yomigaer	to be revived
-KER	keru	ker	to kick
	sikeru	siker	to be moist
	azakeru	azaker	to sneer
-SER	seru	ser	to compete
-SER	aseru	aser	to be impatient
-TER	teru	ter	to shine
-TER	hoteru	hoter	to feel hot
-NER	neru	ner	to knead
	uneru	uner	to wave
	kuneru	kuner	to zigzag
	tuneru	tuner	to pinch
	hineru	hiner	to twist
-HER	heru	her	to decrease
-MER	simeru	simer	to be wet
-GER	kageru	kager	to darken
-GER	sigeru	siger	to grow thick
-BER	syaberu	syaber	to chat
	suberu	suber	to slip
	haberu	haber	to serve

(*1) There are no stems that have the following endings, "NIR", "HIR", "MIR", "RIR", "BIR". If you can exclude such kinds of stems, you may memorize only 20 verbs.

Irregular Inflection

The following conjugations are conformed to Uniformed Regular Conjugation except the perfect forms.

I pick up the following 3 verbs.

iku (to go): The perfect form is not "iita" but "itta".
kou (to ask): The perfect form is not "kotta" but "kouta".
tou (to inquire): The perfect form is not "totta" but "touta".

The following conjugations are conformed to Uniformed Regular Conjugation except the adverbial and "-masu" forms. They are mainly used for honorific expressions.

I pick up the following 5 verbs.

irassyaru (to be/go/come): It is usually used as "irassyai-masu" instead of "irassyari-masu".
ossyaru (to say): It is usually used as "ossyai-masu" instead of "ossyari-masu".
kudasaru (to give): It is usually used as "kudasai-masu" instead of "kudasari-masu".
gozaru (to be): It is usually used as "gozai-masu" instead of "gozari-masu".
nasaru (to do): It is usually used as "nasai-masu" instead of "nasari-masu".

Irregular Conjugation

Logic of Conjugation

Unfortunately, there is no rule to decide any conjugation for this kind of irregular verbs. Now I introduce a table to you so that you know this irregularity. So you do not have to understand them and the best way to learn them is only memorizing them. In the following table, I introduce 2 types of conjugation of "suru". One is modern, the other is classic. Usually we use the modern forms of "suru", but in some special cases, we have to use the classic forms

Irregular Conjugations
	kuru			suru
	kuru			modern			classic
function	raw(*1)	formula	practical	raw(*2)	formula	practical	raw(*3)	formula	practical
negative	ko + anai	[F1]	konai	si + anai	[F1]	sinai	se + azu	[F1]	sezu
adverbial	ki + i	[F1]	ki	si + i	[F1]	si
passive	ko + rareru		korareru	s + rareru	[F2]	sareru	se + rareru		serareru
conditional	ku + reba		kureba	su + reba		sureba
adjectival	ku + ru		kuru	su + ru		suru
causative	ko + saseru		kosaseru	s + saseru	[F2]	saseru	se + saseru		sesaseru
perfect	ki + ta		kita	si + ta		sita
intention	ko + you		koyou	si + you		siyou

(*1) O, I, U are vowel variants.
(*2) I, U are vowel variants.
(*3) E is a vowel variant.

The Final Labyrinth

Finally we have the most serious problem about which is the dominant inflection of "si" that is the adverbial inflection, because the verb "suru" can be combined with many nouns so there are many compound verbs that have the type of irregular conjugation of "suru". We frequently use the adverbial inflection followed by "-masu" as a polite expression. So we have to find out the difference between regular verbs and irregular verbs who have the same adverbial inflection "si".

On the other hand, "kiru" has no problem, you only have to take care of the difference from the verb "kiru", which means "wear" in English.

The following list shows us the "Dominant Adverbial Inflection" provided by irregular verb "suru"

-SSI: e.g. "tas-suru" (to achieve). The type of their conjugation is the classic of "suru".
-NSI: e.g. "kan-suru" (to relate). The type of their conjugation is the classic of "suru".
-UZI: e.g. "kou-zuru" (to lecture). They have a conjugation as a vowel ending stem, too.
-NZI: e.g. "sin-zuru" (to believe). They have a conjugation as a vowel ending stem, too.

The interesting issue related to this labyrinth is that this inflection also confuses a native speaker of Japanese. The adverbial inflection "si" that appears at the end of compound verbs created by "suru" is probably regarded as another one provided by "Uniformed Regular Conjugation". For example, "ai-suru" (to love) is sometimes conjugated as a consonants ending stem just like "ai-su" whose stem is "ai-s". Also "sin-zuru" (to believe) is sometimes conjugated as a vowel ending stem just like "sin-ziru" whose stem is "sin-zi".

Appendixes

Dominant Stem Type -IR

I list up the dominant stems type -IR. The total number of verbs excluding compound verbs is only 27 that is less than the number of recessive stems type -I, indeed. According to this result, you feel curious about why I have defined regressive stems as not -IR but -I. However, type -I is still recessive because its adverbial inflection is confused with one of consonant ending verbs.

Dominant Stems Type -IR (27 words)

	Japanese	basic stem	English
-IR	iru	ir	to get in
	iru	ir	to fry
	hairu	hair	to enter
	mairu	mair	to go
	meiru	meir	to feel depressed
-KIR	kiru	kir	to cut
-KIR	sikiru	sikir	to divide
-SIR	siru	sir	to know
	hasiru	hasir	to run
	musiru	musir	to pluck
	nonosiru	nonosir	to abuse
-TIR	tiru	tir	to fall
-TIR	ketiru	ketir	to scrimp

	Japanese	basic stem	English
-GIR	kagiru	kagir	to ristrict
	kugiru	kugir	to punctuate
	tigiru	tigir	to promise
	tigiru	tigir	to cut up
	nigiru	nigir	to grasp
	uragiru	uragir	to betray
	saegiru	saegir	to interrupt
-ZIR	iziru	izir	to touch
	kaziru	kazir	to bite
	naziru	nazir	to scold
	neziru	nezir	to wrest
	maziru	mazir	to be mixed
	yoziru	yozir	to twist
	huminiziru	huminizir	to tread on

Practices of Conjugations

Practices 1
	negative (-anai)			adverbial (-i)			adjectival (-ru)
basic stem	raw	formula	practical	raw	formula	practical	raw	formula	practical
kar	kar + anai		karanai	kar + i		kari	kar + ru	[F2]	karu
kat	kat + anai		katanai	kat + i		kati	kat + ru	[F2]	katu
kaw	kaw + anai		kawanai	kaw + i		kawi	kaw + ru	[F2]	kawu
kes	kas + anai		kesanai	kes + i		kesi	kes + ru	[F2]	kesu
sin	sin + anai		sinanai	sin + i		sini	sin + ru	[F2]	sinu
tug	kag + anai		tuganai	tug + i		tugi	tug + ru	[F2]	tugu
tuk	kak + anai		tukanai	tuk + i		tuki	tuk + ru	[F2]	tuku
tuke	tuke + anai	[F1]	tukenai	tuke + i	[F1]	tuke	tuke + ru		tukeru
tuki	tuki + anai	[F1]	tukinai	toki + i	[F1]	tuki	tuki + ru		tukiru
yob	yob + anai		yobanai	yob + i		yobi	yob + ru	[F2]	yobu
yom	yom + anai		yomanai	yom + i		yomi	yom + ru	[F2]	yomu

Practices 2
	conditional (-reba)			intention (-you)			perfect (-ta)
basic stem	raw	formula	practical	raw	formula	practical	raw	formula	practical
kar	kar + reba	[F2]	kareba	kar + you	[F2]	karou	kar + ta	[F3]	katta
kat	kat + reba	[F2]	kateba	kat + you	[F2]	katou	kat + ta	[F3]	katta
kaw	kaw + reba	[F2]	kaweba	kaw + you	[F2]	kawou	kaw + ta	[F3]	katta
kes	kes + reba	[F2]	keseba	kes + you	[F2]	kesou	kes + ta	[F3]	kesita
sin	sin + reba	[F2]	sineba	sin + you	[F2]	sinou	sin + ta	[F3]	sinda
tug	tug + reba	[F2]	tugeba	tug + you	[F2]	tugou	tug + ta	[F3]	tuida
tuk	tuk + reba	[F2]	tukeba	tuk + you	[F2]	tukou	tuk + ta	[F3]	tuita
tuke	tuke + reba		tukereba	tuke + you		tukeyou	tuke + ta		tuketa
tuki	tuki + reba		tukireba	tuki + you		tukiyou	tuki + ta		tukita
yom	yom + reba	[F2]	yomeba	yom + you	[F2]	yomou	yom + ta	[F3]	yonda
yob	yob + reba	[F2]	yobeba	yob + you	[F2]	yobou	yob + ta	[F3]	yonda

Practices 3
	causative (-saseru)			passive (-rareru)
basic stem	raw	formula	practical	raw	formula	practical
kar	kar + saseru	[F2]	karaseru	kar + rareru	[F2]	karareru
kat	kat + saseru	[F2]	kataseru	kat + rareru	[F2]	katareru
kaw	kaw + saseru	[F2]	kawaseru	kaw + rareru	[F2]	kawareru
kes	kes + saseru	[F2]	kesaseru	kes + rareru	[F2]	kesareru
sin	sin + saseru	[F2]	sinaseru	sin + rareru	[F2]	sinareru
tug	tug + saseru	[F2]	tugaseru	tug + rareru	[F2]	tugareru
tuk	tuk + saseru	[F2]	tukaseru	tuk + rareru	[F2]	tukareru
tuke	tuke + saseru		tukesaseru	tuke + rareru		tukerareru
tuki	tuki + saseru		tukisaseru	tuki + rareru		tukirareru
yob	yob + saseru	[F2]	yobaseru	yob + rareru	[F2]	yobareru
yom	yom + saseru	[F2]	yomaseru	yom + rareru	[F2]	yomareru