Forming the plural of many nouns ending in -u taken from French.
[French plural form.]
Some French words ending in -eau or -eu brought into English have retained their French plural forms: bureaux, châteaux, milieux, plateaux, tableaux. It is increasingly common to see these with the standard English plural -s instead (see -s1), especially in American English, though châteaux has been least affected. Some have completed the shift: adieus, portmanteaus, purlieus, trousseaus. See also -trix.