Some nouns only have a plural form. They cannot be used with numbers. They include the names of certain tools, instruments and articles of clothing which have two parts.
Well, they are called ‘plurale tantum,’ (pluralia tantum), Latin for ‘plural only’ and used for ‘a noun which is used only in plural form, or which is used only in plural form in a particular sense or senses.’ These nouns are always treated grammatically as plurals: one would say, my trousers are red rather than my trousers is red.
Tools and instruments: Binoculars, headphones, sunglasses, glasses, scissors, tweezers, pliers, forceps, shears, tweezers, and tongs.
Clothing: jeans, pyjamas, tights, knickers, shorts, trousers, pants, and clothes.
- I’ve got new sunglasses. Do you like them?
- He always wears shorts, even in the winter.
A pair of: We can use ‘pair of’ to refer to one example of these nouns:
- I bought a new pair of binoculars last week.
- That old pair of trousers will be useful for doing jobs in the garden.
- We use pairs of to refer to more than one example of this type of noun:
- They’re advertising two pairs of glasses for the price of one.
- I bought three pairs of shorts for the summer.
Other nouns which are always in plural form
Belongings, outskirts, clothes, premises (buildings), congratulations, savings (money), earnings, stairs, goods, surroundings, likes/dislikes, thanks.
- Please ensure that you take all your belongings with you as you leave the aircraft.
- They live on the outskirts of Frankfurt, almost in the countryside.
- My clothes are wet. I’ll have to go upstairs and change.
- She spent all her savings on a trip to South America.
Other examples – Folk, Shenanigans, Loggerheads, Cahoots, Smithereens etc.
Collective nouns (group words):
Some nouns refer to groups of people (e.g. audience, committee, government, team). These are sometimes called collective nouns. Some collective nouns can take a singular or plural verb, depending on whether they are considered as a single unit or as a collection of individuals: Audience, crew, public, committee, enemy, team, company, government, etc.
Nouns used only in the singular
Some nouns are used only in the singular, even though they end in -s. These include: the names of academic subjects such as classics, economics, mathematics/maths, physics; the physical activities gymnastics and aerobics; the diseases measles and mumps; and the word news.
- Maths was never my best subject at school.
- Aerobics is great fun – you should try it!
Such nouns are called singulare tantum (or singularia tantum). It refers to nouns (in any specific sense) that has no plural form and is only used with singular verbs. It is frequently for mass nouns i.e. noun that normally cannot be counted like advice, bread, knowledge, luck, and work etc.
(“Nouns: singular and plural” from English Grammar Today © Cambridge University Press/ 12 nouns that are always plurals. http://blog.oxforddictionaries.com.)