WordNet sense 1 (a professional clown employed to entertain a king or nobleman in the middle ages):

jester, motley fool

WordNet sense 2 (a person who lacks good judgment):

sap, muggins, saphead, tomfool

WordNet sense 3 (a person who is gullible and easy to take advantage of):

chump, gull, mark, mug, patsy, sucker, fall guy, soft touch

WordNet sense 4 (make a fool or dupe of):

befool

WordNet sense 5 (spend frivolously and unwisely):

dissipate, fritter, shoot, fool away, fritter away, frivol away

WordNet sense 6 (fool or hoax):

cod, dupe, slang, put on, take in, put one across, put one over

WordNet sense 7 (indulge in horseplay):

horse around, arse around, fool around