early 15c., in an ecclesiastical sense, "take possession of (a prebend) not rightfully one's own," a back-formation from intrusion, or else from Latin intrudere "to thrust in, force in," from in- "in" (from PIE root *en "in") + trudere "to thrust, push," from PIE *treud- "to press, push, squeeze" (see threat).

From 1560s in a physical sense of "thrust in" (transitive or intransitive); meaning "enter unbidden and without welcome" is from 1570s; that of "thrust or bring in without necessity or right" is from 1580s. Related: Intruded; intruding.

1530s, agent noun from intrude. Originally legal. Fuller ("Pisgah-Sight of Palestine," 1650) has fem. form intrudress.

"intrude where one has no business," especially with a view to gain the advantage or profits of another (as a trader without a proper licence), early 17c., probably a back-formation from interloper (q.v.). Related: Interloped; interloping.

1690s, "to furnish with horns," from horn (n.). Earlier in figurative sense of "to cuckold" (1540s). Meaning "to push with the horns" (of cattle, buffalo, etc.) is from 1851, American English; phrase horn in "intrude" is by 1880, American English, originally cowboy slang. Related: Horned; horning.

1520s, "act of making an indirect suggestion;" 1530s, "that which is indirectly suggested," from French insinuation (16c.) or directly from Latin insinuationem (nominative insinuatio) "entrance through a narrow way; an ingratiating oneself," noun of action from past-participle stem of insinuare "creep in, intrude, wind one's way into" (see insinuate).

1550s, "thrust forward forcibly or unduly" (trans.), from Latin obtrudere "to thrust into, press upon," from ob "in front of; toward" (see ob-) + trudere "to thrust," "to thrust, push," from PIE *treud- "to press, push, squeeze" (see threat). Intransitive sense of "be or become obtrusive, intrude, force oneself" is by 1570s. Related: Obtruded; obtruding.

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.