The middle of the night, especially midnight. [PJC]

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.

by the hour, canonical hour, credit hour, early-morning hour, eleventh hour, happy hour, hour, hour angle, hour circle, hour hand, kilometers per hour, kilometres per hour, kilowatt hour, late-night hour, light hour, man hour, miles per hour, person hour, rush hour, semester hour, sidereal hour, twenty-four hour period, witching, zero hour