Is 'hair' singular or plural?

Question

When one says I was washing my hair, is it singular or plural? What is the singular for hair?

Answer 1

This seems to be one of those plural issues where a different plural is used when referring to the large uncountable group. "I found 3 gray hairs this morning" is proper but so is "I washed my hair this morning".

In the second case, your entire head covered with individuals hairs is treated as a single object or group which is why it is referred to in a singular form.

Answer 2

The word hair in some cases is a collective noun, and in other cases is not a collective noun.

As reported from the NOAD, the meaning of the word is:

1. Any of the fine threadlike strands growing from the skin of humans, mammals, and some other animals.
2. Such strands collectively, especially those growing on a person's head.

In most of the phrases, the word used is hair; in some cases is hairs (to split hairs).

Answer 3

Neither, it is collective, meaning that 'hair' in this context refers to all your hair.

Answer 4

The noun hair is a singular, plural, or collective noun. It all depends on the context of the sentence.

In your sentence,

I was washing my hair.

the noun hair is the collective. It is also the case in:

I have my hair cut.
She brushed her long red hair.

It is singular in following sentences.

I found a hair in my soup.
I just pulled out one of your white hair

It is plural in the following sentences.

There are dog hairs on the sofa.
I lost a lot of hairs after the operation.

Answer 5

I think both hair and hairs are right because the sentence "I pulled out some hairs" would be right and "She has a head full of hair" works too, so I think both hair and hairs work that it just depends on the context clues of the sentence.