-oid Syllabification: (-oid)Definition of -oid suffix forming adjectives and nouns: 1 Zoology denoting an animal belonging to a higher taxon with a name ending in -oidea:hominoid percoid 2denoting form or resemblance:asteroid rhomboidOrigin:from modern Latin -oides, from Greek -oeidēs; related to eidos 'form'-oid in other Oxford dictionaries Definition of -oid in the British & World English dictionary