1. Used to refer to that one previously mentioned. Used of a nonhuman entity; an animate being whose sex is unspecified, unknown, or irrelevant; a group of objects or individuals; or an abstraction:
polished the table until it shone; couldn't find out who it was; opened the meeting by calling it to order.
2. Used as the subject of an impersonal verb:
It is snowing.
3. Used as an anticipatory subject or object:
Is it certain that they will win?
4. Used as an anticipatory subject to emphasize a term that is not itself a subject:
It was on Friday that all the snow fell.
5. Used to refer to a general condition or state of affairs:
She couldn't stand it.
6. Informal Used to refer to something that is the best, the most desirable, or without equal:
He thinks he's it. That steak was really it!
7. Games A player, as in tag, who attempts to find or catch the other players.
8. An animal that has been neutered:
The cat is an it.
9. Middle English
10. from Old English hit * see ko-
源自 古英语 hit *参见 ko-