(1):

(v. t.) To thrust or force (something) in or upon; especially, to force (one's self) in without leave or welcome; as, to intrude one's presence into a conference; to intrude one's opinions upon another.

(2):

(v. t.) The cause to enter or force a way, as into the crevices of rocks.

(3):

(v. t.) To enter by force; to invade.

(4):

(v. i.) To thrust one's self in; to come or go in without invitation, permission, or welcome; to encroach; to trespass; as, to intrude on families at unseasonable hours; to intrude on the lands of another.