WordNet sense 1 (a drink with ice cream floating in it):

ice-cream soda, ice-cream float

WordNet sense 2 (a hand tool with a flat face used for smoothing and finishing the surface of plaster or cement or stucco):

plasterer's float

WordNet sense 3 (be afloat; stay on a liquid surface; not sink):

swim

WordNet sense 4 (be in motion due to some air or water current):

blow, drift, be adrift