Because you need one trouser for each leg - a pair of trousers
Trousers is a plural noun referring to an outer garment covering the body from the waist to the ankles, with a separate part for each leg.
The single form is used in certain circumstances:
I've torn my trouser pocket
She wore a stunning trouser suit
Trouser press
He tore his left trouser leg
Actually both of the answers below are correct - if you're talking about a single kind of ammunition, then the word could be both singular and plural. If you're talking about several kinds of different ammunition, the plural is ammunitions.
The singular form is a pair of trousers; the plural form is pairs of trousers.The noun trousers is one of a group of words that are a short form for 'a pair of', words for things things that require two halves to make one.Some other nouns that are used in their shortened form are pants, shorts, glasses, binoculars, tweezers, tongs, or pajamas. The singular forms are a pair of, the plural form is pairs of.
Singular Plural is caterpillars
The word crisis is singular. The plural form of crisis is crises.
Steroids is plural. The singular form of the word is steroid.
In French, the word for trousers is "pantalon," which is singular. However, when referring to trousers as a pair, it is often treated as plural, as in "des pantalons." So, while "pantalon" is singular, the term for trousers is commonly used in the plural form in everyday language.
The noun 'trousers' an uncountable noun, a form of binary noun, a word for something with two parts making up the whole; a shortened form for 'a pair of'.The singular form is a pair of trousers.The plural form is pairs of trousers.
Slacks (meaning casual trousers) is plural. It has no singular form
Actually both of the answers below are correct - if you're talking about a single kind of ammunition, then the word could be both singular and plural. If you're talking about several kinds of different ammunition, the plural is ammunitions.
The singular form is a pair of trousers; the plural form is pairs of trousers.The noun trousers is one of a group of words that are a short form for 'a pair of', words for things things that require two halves to make one.Some other nouns that are used in their shortened form are pants, shorts, glasses, binoculars, tweezers, tongs, or pajamas. The singular forms are a pair of, the plural form is pairs of.
The word team is singular; the plural form is teams.
These is plural, this is singular
The word breeches is the plural form for the noun breech, a word for the lower part or bottom of something; the opening in the rear of the barrel of a gun where bullets are loaded; a vacant or unobstructed space that is man-made; short for a breech delivery, a birth in which the baby's head does not come out first.The word breeches is also an informal word for trousers, a singular or plural form for a pair of breeches, a pair of trousers. The plural forms are pairs of breeches, pairs of trousers.
Lance is singular. Lances is plural.
The word 'Phenomenon' is singular. The plural form is 'Phenomena'.
The word metastasis is singular, metastases is plural.
The word "ground" can be both singular and plural. Singular: "The ground is wet." Plural: "The grounds of the park are well-maintained."