• By adding –s or –es to nouns ending in -o
• By adding –s to nouns ending in -o.

Singular	Plural		Singular	Plural
buffalo*	buffaloes		potato	potatoes
echo	echoes		tomato	tomatoes
hero	heroes		torpedo	torpedoes
mosquito	mosquitoes		veto	vetoes
negro	negroes		volcano	volcanoes

*The plural form of buffalo can also be buffalo .

• By adding –s or –es to nouns ending in -o
• By adding –s to nouns ending in -o.