Portmanteau (spelling)

Portmanteau is a French word, in the singular. If you want to show off your knowledge of French but write in good English, write the plural of the noun as portmanteaux; portmanteaus is also acceptable in modern English writing. (If you really want to show off your knowledge of French, write the plural with the French spelling - portemanteaux - but remember to put such a foreign word in italics.) When you use the word as an epithet (adjectivally), as in portmanteau word, the plural should not be marked.

You may also want to see portmanteau word and a note on the etymology of words containing the element '-port-'.