Japanese Conjugation of Adjectives

Japanese Conjugation
(Note: This page covers the Japanese conjugation of adjectives.  If you’re looking for information on verbs, check out the Japanese conjugation page on verbs)

Many English-speakers may think that it is strange to conjugate adjectives.  I will admit that the concept is difficult to wrap your mind around at first, but when you accept it and start conjugating adjectives in your everyday Japanese sentences, you will get the hang of it quickly and it will seem like second nature to you.

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Adjectives in Japanese are conjugated when they are the predicate of the sentence and not when they are describing an object.  or example:

Kouhii wa oishii desu
Coffee is delicious.

Here the verb oishii (delicous) is the predicate of the sentence.  This adjective will need to conjugated if the tense of the sentence changes.

where as:

Kore wa oishii koukii desu.
This is delicious coffee.

Here the adjective oishii comes before the word coffee and is directly describing it.  In this case, the adjective oishii does not need to be conjugated if the sentence tense were to change.  Only the verb needs to be conjugated.

In Japanese there are two types of adjectives:  adjective ending in -i and adjectives ending in -na.  We will be taking a look at each type separately.

Japanese Conjugation of Adjectives Ending in -i

As is the case with your Japanese verbs, the adjectives can be conjugated into the present tense and past tense.  Additionally the adjectives will have a positive and negative tense as well, making for a total of 4 different forms of the adjective.

Past tense:

Remove the -i from the end of the adjective and replace it with -katta.

oishii – i = oishi
oishi + katta = oishikatta

Kouhii wa oishikatta desu
The coffee was delicious.

Present negative tense:

Here there are two options.  You change the -i to -ku and then you either add -nai desu or -arimasen to the end.

oishii – i = oishi
oishi + ku = oishiku
oishiku + nai desu = oishiku nai desu
oishiku + arimasen = oishiku arimasen

Kouhii wa oishiku arimasen
The coffee is not delicious.

Past negative tense:

Here there are also two options.  You change the -i to -ku and then either add -nakatta desu or -arimasen deshita.

oishii – i = oishi
oishi + ku = oishiku
oishiku + nakatta desu = oishiku nakatta desu
oishiku + arimasen deshita = oishiku arimasen deshita

Kouhii wa oishiku arimasen deshita
The coffee was not delcious.

Japanese Conjugation of Adjectives Ending in -na

Past tense:

Drop -na and add -deshita

kireina – na = kirei
kirei + deshita = kirei deshita

Present negative tense

Drop -na and add -dewa arimasen

kireina – na = kirei
kirei + dewa arimasen = kirei dewa arimasen

Past negative tense

Drop -na and add -dewa arimasen deshita

kireina – na = kirei
kirei + dewa arimasen deshita = kerei dewa arimasen deshita

These are the basics of Japanese conjugation of adjectives.  Practice these and make sure you memorize which adjectives are -i and -na adjectives.  Get in the habit of conjugating your adjectives and pretty soon this strange grammatical rule will seem completely natural to you.

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