Etimology
From Middle English þei, borrowed in the 1200s from Old Norse þeir, plural of the demonstrative sá which acted as a plural pronoun. Displaced native Middle English he from Old English hīe — which vowel changes had left indistinct from he (“he”) — by the 1400s, being readily incorporated alongside native words beginning with the same sound (the, that, this). Used as a singular pronoun since 1300, e.g. in the 1325 Cursor Mundi. The Norse term (whence also Icelandic þeir (“they”), Faroese teir (“they”), Danish de (“they”), Swedish de (“they”), Norwegian Nynorsk dei (“they”)) is from Proto-Germanic *þai (“those”) (from Proto-Indo-European *to- (“that”)), whence also Old English þā (“those”) (whence obsolete English tho), Scots thae, thai, thay (“they; those”). The origin of the determiner they (“the, those”) is unclear. The OED, English Dialect Dictionary and Middle English Dictionary define it and its Middle English predecessor thei as a demonstrative determiner or adjective meaning "those" or "the". This could be a continuation of the use of the English pronoun they's Old Norse etymon þeir as a demonstrative meaning "those", but the OED and EDD say it is limited to southern, especially southwestern, England, specifically outside the region of Norse contact.
pronoun
they (third-person, nominative case, usually plural, sometimes singular, objective case them, possessive their, possessive noun theirs, reflexive themselves, or reflexive singular themself)
(the third-person plural nominative) A group of entities previously mentioned. [since the 1200s]
(the third-person singular nominative, occasionally proscribed) A single person, previously mentioned, but typically not if previously named and identified as male or female, especially if of unknown, irrelevant or (since 21st century) non-binary gender. [since the 1300s]
(indefinite pronoun, vague meaning) People; some people; people in general; someone, excluding the speaker.
(indefinite pronoun) The authorities: government, police, employers, etc.
(bridge) The opponents of the side which is keeping score.
Examples
Fred and Jane? They just arrived.
Dogs may bark if they want to be fed.
Plants wilt if they are not watered.
I have a car and a truck, but they are both broken.
[…] purſued his vnneighbourly purpoſe in ſuch ſort: that hee being the ſtronger perſwader, and ſhe too credulous in beleeuing or elſe ouer-feeble in reſiſting, from priuate imparlance, they fell to action; and continued their cloſe fight a long while together, vnſeene and vvithout ſuſpition, no doubt to their equall ioy and contentment.
There is no reason to be scared of iguanas. They do not attack humans.
They requested a seat at Friday's performance but didn't say if they preferred the balcony or the floor.
If someone enters the restricted area, they are required to present identification.
Then shalt thou bring forth that man, or that woman vnto thy gates, euen that man, or that woman, and shalt stone them with stones till they die.
Someone knocked into Harry as they hurried past him. It was Hermione.
One thing a nominee earns is the right to pick the vice president that they think will best reflect their vision of the country, and I am just glad I will have nothing to do with it.
The boycott, led by Elisha Lim, of a Toronto gay and lesbian newspaper after it refused to use their preferred pronoun ["they"], citing grammar considerations, inspired me.
I'm angry that we're here again, that we have had to tell another mother that their child is dead.
They say it’s a good place to live.
They didn’t have computers in the old days.
Coordinate terms: one, generic you
I am beautiful, no matter what they say
They'll tax us for the air we breathe next.
They should increase our wages.
Ha, you believe the moon is real? That's just what they want you to think.
Antonym: we
determiner
they
(now Southern England dialect or nonstandard) The, those. [from 14th c.]
(US dialects, including African-American Vernacular) Their. [from 19th c.]
Examples
"They rooks as you see [...] only coom a few year agoo."
Darn'd if they Cockney Chaps can zee there worn't nort but lie in him.
page 21: "But you spile [spoil] they gals - they won't be for no good, they won't."page 30: "'Twas all about they rewks [rooks]," he sobbed.page 54: "mucking the place up with they weeds"
"Bodies and souls," she cried, "if I didn't reckon to have hidden they boots safe from un in the stick-rick." "Off wi' they tight-wasted shoes o' yours, Martha."
Forty quid a fuckin ticket. No shy they British Rail cunts, ah kin fuckin tell ye.
MARY ELLEN is a different case from the others. She has five children and, she claims: "I don't know who they father is. I ain't never kept track. They is always another one. You know, I can catch me a guy[.]"
But all they kids be listenin' to me religiously / So I'm signin' CDs while police fingerprint me
I got bitches askin' me about the code for the Wi-Fi / So they can talk about they timeline / And show me pictures of they friends
He guessed one of the well-off people living in these houses must have took a shine to Cody and decided how he'd look good stuck up on they roof.
Etimology
From earlier the'e, from there.
pronoun
they
(US dialectal) There (especially as an expletive subject of be). [from 19th c.]
Examples
They’s music in the twitter of the bluebird and the jay.
MARY ELLEN is a different case from the others. She has five children and, she claims: "I don't know who they father is. I ain't never kept track. They is always another one. You know, I can catch me a guy[.]"
They ain’t nothin’ wrong with that.
But they ain’t nothin’ in there you didn’t already have.
Well, they’s a lot of ‘em didn’t survive, if you believe me.