さ
冴

え

る

Ichidan verb, intransitive verb

1. to be clear (of a sight, sound, color, etc.), to be bright, to be vivid, to be crisp.
2. to be clear-headed, to be alert, to be on the ball, to be wide awake.
3. to look upbeat, to be perky, to be cheerful. Often as 冴えない.
4. to master (a skill), to excel at, to cleanly execute.
5. to be satisfying. Often as 冴えない.
6. to become frigid, to become intensely cold. Original meaning; now somewhat old-fashioned.