目めざとい

め

ざ

と

い

JLPTN1

Meanings

1

i-adjective

sharp-eyed; keen-eyed; observant

Describes someone who quickly notices details or changes, often with a nuance of being alert or shrewd.

A keen-eyed reader would notice this contradiction.

2

i-adjective

easily awakened; light sleeper

Used for someone who wakes up at the slightest noise or disturbance; often appears as 目ざとい人 or 目ざとい性格.

鋭するどい
鋭い means 'sharp' in a broader sense (knife, mind, glance), while 目ざとい specifically refers to visual alertness or being easily awakened.
敏びん感かん
敏感 means 'sensitive' in general (to stimuli, emotions), whereas 目ざとい is limited to quick visual perception or light sleeping.

Compound of 目 (eye) and ざとい, an old adjective meaning 'quick' or 'sharp'. The exact derivation of ざとい is uncertain.