1. Beauty

The noun BEAUTY when referring to ‘combination of qualities that give pleasure to the senses’ (especially the eye and the ear) or referring to the ‘moral sense or intellectual’, is an uncountable noun and hence has no plural form, and is always singular. But when BEAUTY referring to ‘a beautiful person, thing, characteristics, etc.’ it’s a countable noun and hence forms its singular and plural forms as usual; e.g.

a) She was renowned for her beauty.
b) She was a great beauty (= a beautiful woman) when she was young.
c) We always find new beauties in Shakespeare’s plays.
d) Her smile is one of her beauties.
e) She showed me her car – it’s a beauty.

2. Cloth

When the noun CLOTH is referring to MATERIAL (wool, cotton, etc.) it’s uncountable and hence has no plural form, and is always singular.

INCORRECT: I cut up strips of cotton cloths.
CORRECT: I cut up strips of cotton cloth.

INCORRECT: The women wove cloths for a living.
CORRECT: The women wove cloth for a living.

But when CLOTH is referring to A PIECE OF CLOTH for example, used for cleaning or dusting, it’s a countable noun. In this meaning the plural of CLOTH is CLOTHS (not CLOTHES).

a) Clean with a soft cloth dipped in warm soapy water.
b) Don’t leave damp cloths in a cupboard.
c) Please give me a cloth to clean my shoes.

When we mean the things that we wear such as shirts, trousers, dresses, and coats, we use the word CLOTHES. There is no singular form of CLOTHES

I took off all my clothes.

3. Force

The noun FORCE when is referring to STRENGTH OR ENERGY AS AN ATTRIBUTE OF PHYSICAL ACTION OR MOVEMENT, is a singular uncountable noun, and therefore has no plural form, and takes a singular verb; e.g.

a) The force of character is above all.
b) Teachers aren’t allowed to use force in the classroom.

But it is a singular countable noun when referring to A THING OR PERSON WHO BRINGS A BIG CHANGE. In this use we use ‘A’ before it and form its plural by adding ‘s’; e.g.

a) Religion is a force in everybody’s life.
b) Fishermen are always at the mercy of the forces of nature (= bad weather conditions).

But FORCE when refers to AN ORGANISED MILITARY FORCE form its singular and plural forms as usual; e.g.

a) He joined the police force right after graduating.
b) I’m going to join a force when grown up.
c) I’m in the air force.
d) Security forces halted the demonstrators by blocking the road.

4. Fruit

The noun FRUIT when refers to a name of fruit like apple, orange, mango, etc. it’s a singular uncountable noun. Therefore we do not use ‘A’ before it in singular use, nor do we form its plural by adding ‘s’; e.g.

a) Fruit is not very expensive these days.
b) Vitamin C is found in oranges and other citrus fruit.
c) Go to buy some fruit from the market.

But when it refers to KIND OF FRUIT, it’s a countable noun and from its singular and plural forms as usual; e.g.

a) A mango is a fruit. (a kind of fruit)
b) An apple and a banana are two fruits. (two kinds of fruit)

Fruit when means PROFIT, RESULT, REWARD, etc., can be used in the singular as well as in the plural; e.g.

a) This book is the fruit of 15 years’ research.
b) It’s been hard work, but now the business is running smoothly, you can sit back and enjoy the fruits of your labours.
c) The fruits of industry are always sweet.

5. Look

The noun LOOK when referring to FACIAL EXPRESSION, SEEING, OBSERVATION, etc. is a countable noun, and therefore forms its singular and plural forms as usual; e.g.

a) Can I have a look at your book?
b) Bring your son to the clinic and we’ll take a look at him.
c) He cast a quick look in the rear mirror of the car.
d) I took one look at her and burst out laughing.​
e) I had another look for the book, but couldn’t find
f) She had a worried look about her.

But when it’s referring to PERSON’S APPEARANCE we use it only in the plural; e.g.

a) Her looks are very attractive. (here LOOKS = appearance)
b) Ritu has lost her looks. (here LOOKS = beauty)
c) I like her looks.
d) Her looks improved as she grew older.
e) He put on weight and started to lose his looks.

6. Mankind

The noun MANKIND is always used as a singular noun and takes a singular verb, singular pronoun and singular possessive.

a) Mankind has always been obsessed by power.
b) He worked for the benefit of all mankind.
c) Mankind has not changed.

7. Manner

The noun MANNER when is referring to WAY IN WHICH A THING IS DONE OR HAPPENS, is a countable noun, and therefore forms its singular and plural forms as usual; e.g.

a) He does everything in a simple manner.
b) It can be done in two manners.
c) She stared at me in an accusing
d) He was elected in the normal manner.

The noun MANNER when is referring to PERSON’S WAY OF BEHAVING TOWARDS OTHERS, is always used in the singular; e.g.

a) I don’t like his rude manner.
b) She has a somewhat cold, unfriendly
c) As soon as he realized that we weren’t going to buy anything, his whole manner changed.
d) He behaved in a strange manner.

But when the noun MANNER is referring to HABITS AND CUSTOMS, SOCIAL BEHAVIOR, we use it in the plural form; e.g.

a) He needs to be taught some manners.
b) It’s bad manners to eat with your mouth open.
c) My mother is strict about manners.
d) It is bad manners to stare at girls.

8. Marriage

The noun MARRIAGE when refers to WEDDING in a general sense, is then an uncountable noun and is used in singular form; e.g.

a) Sex before marriage is strongly disapproved of in some cultures.
b) Marriage is the last thing on my mind.

But when the noun MARRIAGE refers to ‘the ceremony of being married’, or ‘the relationship between two persons who are married’, it’s then countable noun, and therefore forms its singular and plural forms as usual; e.g.

a) Rohit and Rani had an arranged marriage.
b) Two marriages are to take place in my village next week.
c) They had a long and happy marriage.
d) Most marriages end in divorce these days.
e) In true Bollywood style, she’s had four marriages.

9. Time

When noun TIME is referring to ‘all the days of the past, present and future, or passing of all the days, months, and years taken as a whole’, it’s a singular uncountable noun, and therefore does not take A/AN in the singular, also its plural is not made by adding ‘s’; e.g.

a) Time waits for nothing.
b) He wants to spend more time with his family.
c) Time passes so quickly when you’re having fun.
d) Have a good time.
e) You’ll forget her in time (= in the future).
f) She’s been called the greatest singer of all time.

When the noun TIME is referring to an ‘occasion to tell its frequency, or good/bad (qualitative adjectives)’, it’s then a countable noun, and therefore forms its singular and plural forms as usual; e.g.

a) Every time I met her, I forgot her name.
b) After a time, it became clear that nobody was interested in coming to the meetings.
c) She came to me three times last month.
d) They stayed with us for a short time.
e) I think this is the best time of her life.

10. Troops

The noun TROOP when refers to ‘group or crowd of people or animals’, is a countable noun, and therefore forms its singular and plural forms as usual; e.g.

i) a) a troop of scouts
b) four troops of scouts

ii) a) a troop of horses
b) four troops of horses

But the noun TROOP when refers to SOLDIERS, it’s always used in the plural and takes a plural verb, and we form its plural by adding ‘s’; e.g.

a) All troops will be withdrawn by the end of the year.
b) The troops always are watchful here.
c) The Chief of Police ordered the deployment of 2,000 troops to try to stop the rioting.
d) Four soldiers were detailed to check the road for troops.

11. Summons

SUMMONS is singular countable noun. Therefore we put A/AN before it in its singular use; if SUMMONS is not in its specific use, and form its plural by adding ‘es’; e.g.

a) The court issued him a summons yesterday.
b) A summons has been issued to you.
c) The summons made her tense. (specific use)
d) The court has issued five summonses today. (plural use)

12.  Wages

WAGES when means MONEY EARNED takes plural verb only, but when means OUTCOME/RESULT can take either of a singular verb and a plural verb; e.g.

INCORRECT: Wages is paid weekly here. (earning)
CORRECT: Wages are paid weekly here.

13. Youth

YOUTH can be used as an uncountable noun also. When an uncountable noun YOUTH means ‘the state or time of being young’. As an uncountable noun it takes a singular verb; e.g.

My youth was a mixture of both happiness and sadness.

YOUTH can also be used as a countable noun. When a countable noun YOUTH means ‘young man’. Its plural, then, is YOUTHS. The verb therefore depends on whether the use is in the singular or plural; e.g.

a) A youth is wants to meet you.
b) Two youths want to meet you.