celluloid Syllabification: (cel·lu·loid)Pronunciation: /ˈselyəˌloid/Translate celluloid | into Italian | into Spanish Definition of celluloid noun a transparent flammable plastic made in sheets from camphor and nitrocellulose, formerly used for cinematographic film. motion pictures as a genre:having made the leap from theater to celluloid, she can now make more moneyOrigin: mid 19th century: from cellulose + -oidcelluloid in other Oxford dictionaries Definition of celluloid in the British & World English dictionary