set to verb 2set-to noun 1forms 3 verb2 •To begin something with determination; to commence a long and difficult task or project.Having laid out the picnic, the hungry boys set to with gusto. •(no longer used) To fight.I set to with the rude man. set-to noun1 •(informal) A fight.[…] we two had never had a serious quarrel, though I had had many a set-to with other lads, and had twice over given Bob Chowne black eyes. — 1887 formssetting to · sets to · set-tos