愉快
yūkuài · HSK 6
be happy
🎉 愉 pleased + 快 quick — happiness that hits fast
快 originally means fast, so 愉快 is pleasure that comes on quickly — an upbeat, breezy kind of cheerful.
快 — heart radical 忄 + 夬 (phonetic)
快 is a semantic-phonetic compound. The heart radical 忄 carries the meaning, since the original sense referred to a feeling of pleasure or delight. The right side 夬 supplies the sound. The meaning later extended from 'pleased' to 'quick, fast', the dominant modern sense.