collective and compound nouns in English

Collective Nouns 
Collective nouns are names for a group of individuals or a number of animals, places, things,
objects, concepts or ideas, for example: 
a herd of elephants, a range of mountains, a gang of thieves, a pack of cards, a board of directors.

Words like army, audience, band, committee, crew, crowd, flock, herd, hive, public, staff, team 
are examples of collective nouns.

These nouns take a singular verb when we think of the group as an entity :

• The audience was enthusiastic.
• Our team is definitely the best.
• The jury is deliberating.

We can use a plural verb if we think of them as members of a  group acting individually :

• The crew are all wearing their new uniform.

Compound nouns

Compound nouns (or compound words) result from the merging of two words. These are 
very common in English and new combinations are invented almost every day.

Compound nouns normally consist of two or three parts, for example washing machine.
The second part (machine) identifies the object or person.
The first part (washing) tells us what sort of object or person it is, or what its purpose is. 

The parts that compose a compound noun can be, for example :

• two nouns (notebook, toothbrush, motorcycle)
• an adjective and a noun (greenhouse, blackboard, software)
• a noun and a verb (rainfall, sunshine, haircut)
• a verb and an adverb (drawback, takeover)
• an adverb and a verb (outbreak, overthrow, input)
• the gerund form of a verb (-ing) with a noun (washing machine, swimming pool)

Compound nouns are either written as :

• separate words (ex: orange juice, real estate, post office, car park),
• words linked by a hyphen (mother-in-law, washing-up, check-in)
• or one word (notebook, classroom, football, bedroom, toothpaste).

It should be noted that compound nouns often have a meaning that is different from the two
separate words. For example: 

- a greenhouse (compound noun) is a place where we grow plants.
- a green house (adjective and noun) is simply a house painted green.