(1):
(v. t.) To exert physical or intellectual strength for the attainment of; to use efforts to effect; to strive to achieve or reach; to try; to attempt.
(2):
(n.) An exertion of physical or intellectual strength toward the attainment of an object; a systematic or continuous attempt; an effort; a trial.
(3):
(v. i.) To exert one's self; to work for a certain end.