1 before anything or anyone else: She reached the top of the hill first. | It's mine, I saw it first.—see firstly2 the first someone or something that is before other people or things : be (the) first to do sth: My sister said I'd be first to get married, but she was wrong. | come (in) first (=win a race): Lewis came first in the 100m race.3 before doing anything else, or before anything else happens: I always read the funnies first. | First I have to clean up the house, then I'll come shopping with you. | first of all: First of all we'd better make sure we have everything we need.4 make the first move to be the person who does something when everyone is nervous and uncomfortable about starting to do something: Barney really likes Hannah, but he's too shy to make the first move.5 do/say sth in the first place spoken used to say that someone said or did something before: I don't really want to go....” Oh Well, why didn't you say so in the first place?”6 in the first instance especially BrE before you do anything else: It is important in the first instance to be sure that there is a demand for the product you wish to sell.THE FIRST TIME STH HAPPENS OR IS DONE7 happening or done before other events or actions of the same kind: He made his first appearance on the stage in the 1950s. | My first reaction was that the story couldn't possibly be true. | the first time: The first time I flew in a plane I was really nervous.8 done for the first time: The book was first published in Australia last year.9 the first someone who does something that has never been done or happened before: No one had ever settled in the valley before; he was the first. | be the first to do sth: She was the first to see the importance of the nineteenth century writers in this context.10 a first something that has never been done or happened before: Roger Bannister's four-minute mile was a notable first in the history of athletics.11 at first glance/sight the first time that you see something, before you notice much detail: At first glance the twins look identical.12 first come, first served used to say that people who arrive, ask etc before other people, will be dealt with or given something before themBEGINNING13 the first the people or things at the beginning of a row, line, series, period of time etc: the first Monday of every month | for the first six months of my time in Nepal | the first chapter of the book14 at the beginning of a situation or activity: When we were first married, we lived in Toronto. | We first became friends when we were teenagers.15 at first in the beginning: Alistair felt tired at first, but soon got used to the long working hours.—compare at last last 3 (2), —see firstly16 from the (very) first from the beginning: The relationship was doomed to failure from the first.MAIN/IMPORTANT17 being the most important or main thing: The first priority is to maintain the standard of work.18 first things first used to tell someone to deal with things in order of importance19 put sth first to make something the most important thing: Rob seems to put money first, and happiness second in his life.20 come first to be the most important thing to someone(+ with): Alma's family will always come first with her.21 first and foremost as the main reason for or purpose of something: The aim of the exercise was first and foremost to give confidence to the students.22 first among equals someone who leads a group of people but is not considered to be more important than themTHE FIRST REASON/FACT ETC23 used to give an important fact or reason that will be followed by others: Well, first, the building is too small, and second, it isn't in a very good location.24 first of all spoken used to introduce the first thing that you are going to talk about: First of all I'd like to welcome you to the meeting.25 first off spoken used to introduce a fact, reason, or statement that will be followed by others, especially when you are annoyed with someone: First off, you should have told me where you were going.26 in the first place spoken used to give a fact or reason that proves what you are saying in an argument : Well, in the first place, Quinn would never say any such thing.—see firstly BEST27 first choice the thing or person you like best: Frances was our first choice as a name for the baby.28 come first/win first prize to be the best in a competition: My jam won first prize at the county fair.29 a first the highest level of university degree you can get in Britain : get a first (in): Helen got a first in Law.30 of the first water old-fashioned of the highest quality: a jewel of the first waterMORNING31 first thing as soon as you get up in the morning, or as soon as you start work: The boss was here first thing, but he's gone to Newcastle now. | I'll phone him first thing Monday.32 at first light very early in the morning: They left at first light and were in the mountains by nightfall.NOT KNOW33 not have the first idea about/not know the first thing about to not know anything about a subject, or not know how to do something: I wouldn't have the first idea about what to do in an emergency. | I don't know the first thing about cars.34 the first I (have) heard/I knew etc of it spoken used when you have just found out about something that other people already know, and are slightly annoyed about it: Andrew's been promoted? That's the first I've heard about it.OTHER MEANINGS35 (at) first hand if you hear or experience something at first hand, you hear etc it directly, not through other people: The school had to deal first hand with the social problems of the area.36 firsta) first gear; the lowest gear 1 (2) in a car, bicycle, or other vehicle, that you use to begin moving : be in first: Put the car in first when you park on a hill.b) AmE first base37 I'd die/kill myself etc first spoken used to emphasize how strongly you do not want to do something: I'll never take him back. I'd die first!
Longman dictionary of contemporary English. 2004.