Word Origin & History
deepO.E. deop, from P.Gmc. *deupaz, from PIE *d(e)u- "deep, hollow" (cf. O.C.S. duno "bottom, foundation," O.Ir. domun "world," via sense development from "bottom" to "foundation" to "earth" to "world"). Figurative sense was in O.E.; extended 16c. to color, sound. Deep pocket "wealth" is from 1951. Deep-freeze
EXPANDwas a registered trademark (U.S. Patent Office, 1941) of a type of refrigerator; used generically for "cold storage" since 1949. To go off the deep end "lose control of oneself" is slang first recorded 1921, probably in reference to the deep end of a swimming pool, where a person on the surface can no longer touch bottom. When 3-D films seemed destined to be the next wave and the biggest thing to hit cinema since "talkies," they were known as deepies (1953). The gods have spared us.
deeplyO.E. deoplice (see
deep), used in both literal and figurative senses.
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