sinuate adj.

early 15c., in anatomy, "hollow curve or cavity in the body" (Chauliac), from Medieval Latin sinus, from Latin sinus "bend, fold, curve, a bent surface; a bay, bight, gulf; a fold in land;" also "fold of the toga about the breast," hence "bosom," and figuratively "love, affection, intimacy; interior, inmost part;" a word of unknown origin. De Vaan writes that it is "probably to be connected with" Albanian gji "breast." In 17c.-18c. English writers also sometimes used it in the classical senses of "a bay, gulf, or arm of the sea; a cavity or hole in the earth," but these uses are obsolete.

1520s, "to covertly and subtly introduce into the mind or heart" (trans.), from Latin insinuatus, past participle of insinuare "to thrust in, push in, make a way; creep in, intrude, bring in by windings and curvings, wind one's way into," from in- "in" (from PIE root *en "in") + sinuare "to wind, bend, curve," from sinus "a curve, winding" (see sinus).

Intransitive meaning "hint obliquely" is from 1560s. Meaning "maneuver (someone or something) into some desired position or condition" is from 1570s. Physical or literal sense of "to introduce tortuously or indirectly" is from 1640s. Related: Insinuated; insinuating.