The descent of the sun below the horizon; also, the time when the sun sets; evening. Also used figuratively. [1913 Webster]
"'T is the sunset of life gives me mystical lore." [1913 Webster]
Hence, the region where the sun sets; the west. [1913 Webster]

Sunset shell (Zoöl.), 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.

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OXFORD DICTIONARY

sunset, n.
1 the sun's setting in the evening.
2 the coloured sky associated with this.
3 the time at which sunset occurs.
4 the declining period of life.

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THESAURUS

sunset

cardinal points, close of day, cockshut, compass card, compass rose, degrees, east, eastward, eve, even, evening, evensong, eventide, grayness, half points, lubber line, nightfall, north, northeast, northward, northwest, occident, orient, quarter points, rhumb, setting sun, shut of day, south, southeast, southward, southwest, sundown, sunrise, the expiring day, twilight, vesper, west, westward

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ROGET THESAURUS

sunset

Evening

N evening, eve, decline of day, fall of day, close of day, candlelight, candlelighting, eventide, nightfall, curfew, dusk, twilight, eleventh hour, sunset, sundown, going down of the sun, cock-shut, dewy eve, gloaming, bedtime, afternoon, postmeridian, p, m, autumn, fall, fall of the leaf, autumnal equinox, Indian summer, St. Luke's summer, St. Martin's summer, midnight, dead of night, witching hour, witching hour of night, witching time of night, winter, killing time, vespertine, autumnal, nocturnal, midnight, the outpost of advancing day, sable-vested Night, this gorgeous arch with golden worlds inlay'd.

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