noun
evening; early night
Refers to the period from dusk until late evening, often with a poetic or literary feel. In modern casual speech, 夕方 or 夜 are more common.
宵のうちに雨が上がった。
The rain stopped in the early evening.
宵の明星が西の空に輝いている。
The evening star is shining in the western sky.
夕方 is the common everyday word for 'evening' or 'late afternoon'; 宵 is more literary and often refers to the darker part of early night.
夜 is the general word for 'night'; 宵 specifically refers to the early part of the night, often with a poetic nuance.
The historical derivation is uncertain; the kanji 宵 is conventionally associated with the meaning 'evening' or 'early night'.