I know that the noun looks usually takes plural form, eg:
Her looks are deceptive.
But since looks is an uncountable noun, why does it take a plural verb? Shouldn't it be treated like the other uncountable nouns - love, happiness, news or beauty etc. and be treated as singular? Specially when we use beauty in a similar context, we say -
Her beauty is what makes her special.
but the moment we switch to looks, we say -
Her looks are what make her special.
Can anyone explain why this is so.
I don't think I can give a definitive answer to your excellent question. However, I can point out that there are a few nouns in English which look and sound plural even when they are used as a singular word. When this happens, we sometimes treat the word as though it were plural – perhaps because it just sounds more natural to our ear.
Some examples would include:
These scissors are dull.
There is a hole in these pants! I can't wear them.
These tweezers are sharp! Be careful with them.
Similarly, some English nouns are plural, but they appear singular and therefore are treated as singular words – much to the consternation of some purists:
The data has been corrupted.
Note: some might argue that data is plural and therefore should be treated as a plural word, but there is an interesting blog post about that here. It says (among other things):
It's like agenda, a Latin plural that is now almost universally used as a singular. Technically the singular is datum/agendum, but we feel it sounds increasingly hyper-correct, old-fashioned and pompous to say "the data are".
An EnglishPlus grammar blog post entitled Tricky Plurals points out that branches of knowledge ending with -s (such as physics and ethics) are treated as singulars, as are diseases (such as measles and mumps), while words that end with -s and represent a pair (such as pliers or eyeglasses) are treated as plurals.
I find the word you ask about – looks – rather unique. It's no disease, it's not a branch of knowledge, and it doesn't represent a pair. Wiktionary defines looks with two noun definition:
n.Plural form of look.
n.One's appearance or attractiveness.
In that second usage, you are correct, we typically treat it as a plural noun, even though it's pretty much synonymous with beauty:
Her looks are stunning. Her beauty is stunning.
although we can use look in the singular, too:
She has an alluring look.
"Looks" is a countable noun, which is usually used in the plural, even when the meaning is apparently singular.
A noun used as uncountable is never plural, even when it seems to refer to many things: "This is rice" not *"These are rices". Some nouns are countable but usually plural: trousers, loggerheads, thanks and so on. All are countable and plural, but have no common singular form.
Since "looks" is plural, the verb is "are" for agreement. (third person plural)
There is no special reason for this. English could have evolved differently. But the modern idiom is to use the plural here. Unlike "trousers" the singular "look" is also quite common.
He gave her a long look.
The look of 2019 is short sharply cut miniskirts in bold colours.
