A singular noun names one person, place, thing, or idea. A plural noun names more than one. Most nouns add –s or –es to form the plural. The spelling of some nouns changes when –es is added to form the plural (puppy/puppies; scarf/scarves). A few nouns do not add –s or –es to form the plural; instead, they change spelling (tooth/teeth; child/children). A few other nouns have the same form in the singular and plural (sheep/sheep; deer/deer).