I know in past tense, you use く like 暗くない but even in present tense, I see example phrases where 暗く is used.

For instance:


I'm a beginner so bear with me please and thanks!

  • 1
    in present tense, I see example phrases where 暗く is used That's because く does not indicate past tense. For 暗い past would be 暗かった.
    – By137
    Sep 15, 2021 at 17:51

1 Answer 1



For い-adjectives the く-form is used in a number of contexts.

As you noted, if you wanted to say

It's not dark.

you'd say


If you want to say

It'll get dark.

you'd say


So, in the example sentence you provided


Because it's already gotten dark, let's head home.


And for completeness sake, let's look at how this would correspondingly work for な-adjectives, like きれい

If you wanted to say,

It's not pretty.

you'd say

きれいではない (less formally) きれいじゃない

If you wanted to say

It'll become pretty

then you'd say


Inflected forms for い-adjectives

And because you mentioned the past tense, there are a few more points to be made.

Adjectives (like verbs) inflect in Japanese. For い-adjectives, the inflected form (if it's not plain non-past), the い is dropped and replaced with k. There are then three different usages that follow this pattern

Past tense: くらい => くらかった (it's dark)

Conditional form: くらい => くらければ (if it's dark)

and the く-form you've been encountering

to form a negative: くらくない (it's not dark)

to describe a changing state: くらくなる (it'll get dark)

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