a suffix occurring in words borrowed from French and other Romance languages (bassoon; balloon; dragoon; pontoon), and on this model occasionally used in the formation of new nouns in English (spittoon)
Word origin
[as an English formative (e.g., in spittoon), extracted from words of various origins (buffoon, lagoon, etc.) but repr. chiefly F -on in words stressed on the final syllable; cf. Sp. -on, It. -one, L -ōn-]