良(い)いい-Adjective meaning 'good'

いい is an adjective that means 'good' in Japanese. It can be a little bit difficult to use at first, as it conjugates differently to other い-Adjectives.

In these sentences, we can see that the first い in いい changes to よ, depending on the form. This is unique to いい, and does not happen with other adjectives.

いい can sometimes be seen as 良(よ)い, in these cases, the kanji is likely to be read as よい, and not いい. There is technically no difference between these two meanings, but よい does sound more formal/old-fashioned.

Caution

When used as an adverb, よく should not be confused as a conjugation of いい. よく has several possible kanji that it may stem from, and means frequently/often/well.