Entry 1 sense Webster, 1913 Energizer /ĕn'-ẽrj-īzˌ-ẽr/ · En·er·gi·zer · IPA /ˈɛnərdʒˌaɪzər/ 01 n. One who, or that which, gives energy, or acts in producing an effect. 1. One who, or that which, gives energy, or acts in producing an effect.