Sunset \Sun"set"\, Sunsetting \Sun"set`ting\, n.

1. The descent of the sun below the horizon; also, the time when the sun sets; evening. Also used figuratively.

'T is the sunset of life gives me mystical lore. --Campbell.

2. Hence, the region where the sun sets; the west.

Sunset shell (Zo["o]l.), a West Indian marine bivalve (Tellina radiata) having a smooth shell marked with radiating bands of varied colors resembling those seen at sunset or before sunrise; -- called also rising sun.

Source: Webster's Revised Unabridged Dictionary (1913)