The first thing, person, event, or period of time is the one that happens or comes before all the others of the same kind.

If you do something first, you do it before anyone else does, or before you do anything else.

When something happens or is done for the first time, it has never happened or been done before.

An event that is described as a first has never happened before and is important or exciting.

The first you hear of something or the first you know about it is the time when you first become aware of it.

You use first when you are talking about what happens in the early part of an event or experience, in contrast to what happens later.

In order to emphasize your determination not to do a particular thing, you can say that rather than do it, you would do something else first .

You use first when you are about to give the first in a series of items.

The first thing, person, or place in a line is the one that is nearest to you or nearest to the front.

You use first to refer to the best or most important thing or person of a particular kind.

First is used in the title of the job or position of someone who has a higher rank than anyone else with the same basic job title.

In British universities, a first is an honours degree of the highest standard.

You use first of all to introduce the first of a number of things that you want to say.

You use at first when you are talking about what happens in the early stages of an event or experience, or just after something else has happened, in contrast to what happens later.

If you say that someone or something comes first for a particular person, you mean they treat or consider that person or thing as more important than anything else.

You say 'first come first served' to indicate that a group of people or things will be dealt with or given something in the order in which they arrive.

From the first means ever since something started.

If you learn or experience something at first hand, you experience it yourself or learn it directly rather than being told about it by other people.

If you say that you do not know the first thing about something, you are emphasizing that you know absolutely nothing about it.

You use first off to introduce the first of a number of things that you want to say.

If you put someone or something first, you treat or consider them as more important than anything else.

You say 'first things first' when you are talking about something that should be done or dealt with before anything else because it is the most important.