Noun: photoperiodism ,fow-tow'peer-ee-u,di-zum(biology) the growth, development and other responses of plants and animals to the length of day during the yearDerived forms: photoperiodismsEncyclopedia: PhotoperiodismNearestphotometristphotometryphotomicrographphotomontagephotomosaicphotomultiplierphotonphotonicsphoto-offsetphoto-offset printingphotoperiodismphotophobiaphotophorephotopicphotopic vi