Singular they

Singular they, along with its inflected or derivative forms, them, their, theirs, and themselves, is a gender-neutral third-person pronoun derived from plural they. It typically occurs with an indeterminate antecedent, to refer to an unknown person, or to refer to every person of some group, in sentences such as:
This use of singular they had emerged by the 14th century, about a century after the plural they. Singular they has been criticized since the mid-18th century by prescriptive commentators who consider it an error. Its continued use in modern standard English has become more common and formally accepted with the move toward gender-neutral language. Some early-21st-century style guides described it as colloquial and less appropriate in formal writing. However, by 2020, most style guides and English-learning websites, such as the APA, AP, CMOS, British Council etc. accepted the singular they as a personal pronoun.
In the early 21st century, use of singular they with known individuals emerged for non-binary people, as in, for example, "This is my friend, Jay. I met them at work." They in this context was named Word of the Year for 2015 by the American Dialect Society, and for 2019 by Merriam-Webster. In 2020, the American Dialect Society also selected it as Word of the Decade for the 2010s.

Inflected forms and derivative pronouns

Like the "singular you", "singular they" permits a singular antecedent, but is used with the same verb forms as plural they, and has the same inflected forms as plural they, except that in the reflexive form, themself is sometimes used instead of themselves.

Pronoun	Subjective	Objective			Reflexive
He	is my son.	When my son cries, I hug.	My son tells me age.	If I lose my phone, my son lends me.	My son dresses.
She	is my daughter.	When my daughter cries, I hug.	My daughter tells me age.	If I lose my phone, my daughter lends me.	My daughter dresses.
Plural they	are my children.	When my children cry, I hug.	My children tell me ages.	If I lose my phone, my children lend me.	My children dress.
	are my child.	When my child cries, I hug.	My child tells me age.	If I lose my phone, my child lends me.	My child dresses .
Generic he	is my child.	When my child cries, I hug.	My child tells me age.	If I lose my phone, my child lends me.	My child dresses.
It	is my child.	When my child cries, I hug.	My child tells me age.	If I lose my phone, my child lends me.	My child dresses.

Themself is attested from the 14th to 16th centuries. Its use has been increasing since the 1970s or 1980s, though it is sometimes still classified as "a minority form". In 2002, Payne and Huddleston, in The Cambridge Grammar of the English Language, called its use in standard dialect "rare and acceptable only to a minority of speakers" but "likely to increase with the growing acceptance of they as a singular pronoun". It is useful when referring to a single person of indeterminate gender, where the plural form themselves might seem incongruous, as in:

Regional preferences

The Canadian government recommends themselves as the reflexive form of singular they for use in Canadian federal legislative texts and advises against using themself.

Usage

They with a singular antecedent goes back to the Middle English of the 14th century, and has remained in use for centuries in spite of its proscription by traditional grammarians beginning in the mid-18th century.
Informal spoken English exhibits universal use of the singular they. An examination by Jürgen Gerner of the British National Corpus published in 1998 found that British speakers, regardless of social status, age, sex, or region, used the singular they more often than the gender-neutral he or other options in the context of being anaphors after indefinite pronouns like "everybody" and "anybody".

Prescription of generic ''he''

He has been used with antecedents of indeterminate gender since the Old English period, as in the following:
The earliest known explicit recommendation by a grammarian to use the generic he rather than they in formal English is Ann Fisher's mid-18th century A New Grammar assertion that "The Masculine Person answers to the general Name, which comprehends both Male and Female; as, any Person who knows what he says."
Nineteenth-century grammarians insisted on he as a gender-neutral pronoun on the grounds of number agreement, while rejecting "he or she" as clumsy, and this was widely adopted: e.g. in 1850, the British Parliament passed an act which provided that, when used in acts of Parliament "words importing the masculine gender shall be deemed and taken to include females". Baskervill and Sewell mention the common use of the singular they in their An English Grammar for the Use of High School, Academy and College Class of 1895, but prefer the generic he on the basis of number agreement.
Baskervill gives a number of examples of recognized authors using the singular they, including:
It has been argued that the real motivation for promoting the "generic" he was an androcentric world view, with the default sex of humans being male – and the default gender therefore being masculine. There is some evidence for this: Wilson wrote in 1560:
And Poole wrote in 1646:
In spite of continuous attempts on the part of educationalists to proscribe singular they in favour of he, this advice was ignored; even writers of the period continued to use they. Use of the purportedly gender-neutral he remained acceptable until at least the 1960s, though some uses of he were later criticized as being awkward or silly, for instance when referring to:

Indeterminate persons of both sexes:
Known persons of both sexes:
Contemporary use of ''he'' to refer to a generic or indefinite antecedent

He is still sometimes found in contemporary writing when referring to a generic or indeterminate antecedent. In some cases, it is clear from the situation that the persons potentially referred to are likely to be male, as in:
In some cases the antecedent may refer to persons who are only probably male or to occupations traditionally thought of as male:
In other situations, the antecedent may refer to an indeterminate person of either sex:
In 2010, Choy and Clark still recommend the use of generic he "in formal speech or writing":
In informal spoken English, plural pronouns are often used with indefinite pronoun antecedents. However, this construction is generally not considered appropriate in formal speech or writing.
In 2015, Fowler's Dictionary of Modern English Usage calls this "the now outmoded use of he to mean 'anyone, stating:
In 2016, Garner's Modern English Usage calls the generic use of masculine pronouns "the traditional view, now widely assailed as sexist".

Rise of gender-neutral language

The earliest known attempt to create a new gender-neutral pronoun in English dates back to 1792, when Scottish economist James Anderson of Hermiston advocated for an indeterminate pronoun ou.
In 1808, poet Samuel Taylor Coleridge suggested it and which as neutral pronouns for the word person:
In the second half of the 20th century, people expressed more widespread concern at the use of male-oriented language. This included criticism of the use of man as a generic term to include men and women and of the use of he to refer to any human, regardless of sex.
It was argued that he could not sensibly be used as a generic pronoun understood to include men and women. William Safire in his On Language column in The New York Times approved of the use of generic he, mentioning the mnemonic phrase "the male embraces the female". C. Badendyck from Brooklyn wrote to The New York Times in a reply:
By 1980, the movement toward gender-neutral language had gained wide support, and many organizations, including most publishers, had issued guidelines on the use of gender-neutral language, but stopped short of recommending they to be third-person singular with a non-indeterminate, singular antecedent.

Contemporary usage

The use of masculine generic nouns and pronouns in written and spoken language has decreased since the 1970s.
In a corpus of spontaneous speech collected in Australia in the 1990s, singular they had become the most frequently used generic pronoun. Similarly, a study from 2002 looking at a corpus of American and British newspapers showed a preference for they to be used as a singular epicene pronoun.
The increased use of singular they may owe in part to an increasing desire for gender-neutral language. A solution in formal writing has often been to write "he or she", or something similar, but this is often considered awkward or overly politically correct, particularly when used excessively. In 2016, the journal American Speech published a study by Darren K. LaScotte investigating the pronouns used by native English speakers in informal written responses to questions concerning a subject of unspecified gender, finding that 68% of study participants chose singular they to refer to such an antecedent. Some participants noted that they found constructions such as "he or she" inadequate as they do not include people who identify as neither male nor female.