sunlight; light of day
Literally the light of the sun or daylight. It is more phrase-like than ordinary 日光 and is especially natural in expressions such as 日の目を見る, when the context makes the literal idea of seeing daylight clear.
I worked underground all day and hardly saw the sunlight.
A transparent compound of 日, 'sun' or 'day,' の, and 目. The spelling is conventionally associated with the idea of the sun's light or the light of day; the exact historical nuance of 目 in this expression is not.