germicide Syllabification: (ger·mi·cide)Pronunciation: /ˈjərməˌsīd/Definition of germicide noun a substance or other agent that destroys harmful microorganisms; an antiseptic. Derivatives germicidalPronunciation: /ˌjərməˈsīdl/ adjective germicide in other Oxford dictionaries Definition of germicide in the British & World English dictionary