oversize verb 3adjective 2noun 1forms 5 verb3 •To make larger, or too large. •To exceed in size. •(no longer used) To cover with size or gluey matter. adjective2 •Larger than normal. •Excessively large.Volleyball jerseys are formfitting and cute—unlike the oversize basketball or football ones. — 2009 noun1 •The increased size of the bore of an engine when it is rebored.However, any increase in capacity is useful and, if an engine is worn and needs a rebore, it's worth considering boring to a near maximum size rather than simply having it bored to the next oversize. — 2005 formsoversized · oversizing · oversizes · more oversize · most oversize