1620s, "intensely cold," from Latin frigidus "cold, chill, cool," figuratively "indifferent," also "flat, dull, trivial," from stem of frigere "be cold;" related to noun frigus "cold, coldness, frost," from Proto-Italic *srigos-, from PIE root *srig- "cold" (cognates: Greek rhigos "cold, frost"). The meaning "wanting in sexual heat" is attested from 1650s, originally of males. Related: Frigidly; frigidness.