to take (game or fish) illegally by hunting on land or fishing in an area river without the owner's permission

to take (an ideas, work, etc belonging to somebody else) and use them or it to one's own advantage

to entice (an employee working for another company) to come and work for one's own company

to trespass on (land)

said of a horse or its rider: to cause (land) to break up into muddy patches

said of somebody playing doubles in tennis or badminton: to take or try to take (a shot or shots that belong to their partner)

(+ on) to encroach on somebody else's territory

what happens to a poet when he poaches on a novelist's preserves — Virginia Woolf

said esp of a striker in football: to wait around the opposing team's goal area for a scoring opportunity