overwinter UK /ˌəʊ.vəˈwɪn.tə/US /ˌoʊ.vɚˈwɪn.tɚ/verb 2adjective 1adverb 1forms 3 verb2 •To keep or preserve for the winter.It is best to overwinter tender plants indoors. •To spend the winter (in a particular place).Insects may overwinter in fallen fruit if it is not removed. adjective1 •Occurring over the winter season.The effect of seedling size on overwinter injury was analyzed separately by analysis of covariance. — 1996 adverb1 •During the winter.Ground cover of perennial grasses declined seriously under plots covered overwinter with dead thistle plants. — 1968 formsoverwintered · overwintering · overwinters