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pleasure, enjoyment, fun, amusement
楽しい
fun, enjoyable
音楽を聞くのは楽しい
It's fun to listen to music
easy, simple, no trouble
楽に
easily, with ease
この仕事は楽だ
This job is easy
The character 楽 is often used in combination with other characters to form new words related to pleasure or ease.