intransitive. To lift one's head or stand upright briskly, impudently, inquisitively, etc.; to thrust oneself or one's face forward inquisitively or…

intransitive. To raise oneself to one's full height; to thrust up one's head and stand erect; to perk up. Also figurative. Obsolete.

intransitive for reflexive. To straighten oneself, assume an upright position.

intransitive. To stand straight up; to stick up. Also with up.

intransitive. To become straight. to straighten up (originally U.S.): to rise to an erect posture; slang, to adopt an honest course of life; also in…