WordNet sense 1 (find out, learn, or determine with certainty, usually by making an inquiry or other effort):

ascertain, check, determine, learn, see, watch

WordNet sense 2 (establish after a calculation, investigation, experiment, survey, or study):

find

WordNet sense 3 (trap; especially in an error or in a reprehensible act):

catch out

WordNet sense 4 (get to know or become aware of, usually accidentally):

discover, hear, pick up, get a line, get wind, get word