Forming nouns and derived verbs.
[Originally from French words having the final stressed syllable -on; sometimes via the equivalent Italian -one.]
Examples from French include bassoon (French basson); dragoon (French dragon, a type of musket, thought of as breathing fire like a dragon), now a member of any of several British cavalry regiments; pontoon (French ponton), a flat-bottomed boat used to support a temporary bridge or floating landing stage. Examples from Italian include lagoon (Italian, and Spanish, laguna) and cartoon (Italian cartone). Some can be either nouns or verbs: cocoon, lampoon. The only common word formed in English using this ending is spitoon.
A few words come from other languages and are unconnected: tycoon (Japanese taikun, great lord), monsoon (Portuguese monçäo, from Arabic mawsim, season), raccoon (Virginia Algonquian aroughcun).
See also -zoon.