word-forming element meaning "toward; against; before; near; across; down," also used as an intensive, from Latin ob (prep.) "in the direction of, in front of, before; toward, to, at, upon, about; in the way of; with regard to, because of," from PIE root *epi, also *opi "near, against" (see epi-).

Old English þreat "crowd, troop," also "oppression, coercion, menace," related to þreotan "to trouble, weary," from Proto-Germanic *thrautam (source also of Dutch verdrieten, German verdrießen "to vex"), from PIE *treud- "to push, press squeeze" (source also of Latin trudere "to press, thrust," Old Church Slavonic trudu "oppression," Middle Irish trott "quarrel, conflict," Middle Welsh cythrud "torture, torment, afflict"). Sense of "conditional declaration of hostile intention" was in Old English.

"an undue and unsolicited thrusting forward of something upon the notice or attention of others," 1570s, from Latin obtrusionem (nominative obtrusio), noun of action from past-participle stem of obtrudere "to thrust into, press upon" (see obtrude).

"given to thrusting one's self or one's opinions upon the company or notice of others, characterized by forcibly thrusting (oneself, etc.) into notice or prominence," 1660s, from Latin obtrus-, past participle stem of obtrudere (see obtrude) + -ive. Related: Obtrusively; obtrusiveness.