What does "hark" mean?

Hark: To listen; to hearken. [Now rare, except in the imperative form used as an interjection, Hark! listen.] Hudibras. Hark away! Hark back! Hark forward! (Sporting), cries used to incite and guide hounds in hunting. -- To hark back, to go back for a fresh start, as when one has wandered from his direct course, or made a digression. He must have overshot the mark, and must hark back. Haggard. He harked back to the subject. W. E. Norris.