i-adjective
Describes a sharp, unpleasant taste like coffee, dark chocolate, or medicine. Also used figuratively for a bitter experience or feeling.
このコーヒーは苦い。
This coffee is bitter.
苦い経験をした。
I had a bitter experience.
Standard kanji spelling; high-frequency word.
Native Japanese adjective. The kanji 苦 is used for its meaning 'bitter, painful', but the reading にがい is not derived from Chinese.