'They' definitions:

Definition of 'They'

From: GCIDE

He \He\ (h[=e]), pron. [nom. He; poss. His (h[i^]z); obj. Him (h[i^]m); pl. nom. They ([th][=a]); poss. Their or Theirs ([th][^a]rz or [th][=a]rz); obj. Them ([th][e^]m).] [AS. h[=e], masc., he['o], fem., hit, neut.; pl. h[imac], or hie, hig; akin to OFries. hi, D. hij, OS. he, hi, G. heute to-day, Goth. himma, dat. masc., this, hina, accus. masc., and hita, accus. neut., and prob. to L. his this. [root]183. Cf. It.]
1. The man or male being (or object personified to which the masculine gender is assigned), previously designated; a pronoun of the masculine gender, usually referring to a specified subject already indicated. [1913 Webster]
Thy desire shall be to thy husband, and he shall rule over thee. --Gen. iii. 16. [1913 Webster]
Thou shalt fear the Lord thy God; him shalt thou serve. --Deut. x. 20. [1913 Webster]
2. Any one; the man or person; -- used indefinitely, and usually followed by a relative pronoun. [1913 Webster]
He that walketh with wise men shall be wise. --Prov. xiii. 20. [1913 Webster]
3. Man; a male; any male person; -- in this sense used substantively. --Chaucer. [1913 Webster]
I stand to answer thee, Or any he, the proudest of thy sort. --Shak. [1913 Webster]
Note: When a collective noun or a class is referred to, he is of common gender. In early English, he referred to a feminine or neuter noun, or to one in the plural, as well as to noun in the masculine singular. In composition, he denotes a male animal; as, a he-goat. [1913 Webster]

From: GCIDE

They \They\ ([th][=a]), pron. pl.; poss. Theirs; obj. Them. [Icel. [thorn]eir they, properly nom. pl. masc. of s[=a], s[=u], [thorn]at, a demonstrative pronoun, akin to the English definite article, AS. s[=e], se['o], [eth]aet, nom. pl. [eth][=a]. See That.] The plural of he, she, or it. They is never used adjectively, but always as a pronoun proper, and sometimes refers to persons without an antecedent expressed. [1913 Webster]
Jolif and glad they went unto here [their] rest And casten hem [them] full early for to sail. --Chaucer. [1913 Webster]
They of Italy salute you. --Heb. xiii. 24. [1913 Webster]
Blessed are they which do hunger and thirst after righteousness. --Matt. v. 6. [1913 Webster]
Note: They is used indefinitely, as our ancestors used man, and as the French use on; as, they say (French on dit), that is, it is said by persons not specified. [1913 Webster]

From: GCIDE

She \She\, pron. [sing. nom. She; poss. Her. or Hers; obj. Her; pl. nom. They; poss. Theiror Theirs; obj. Them.] [OE. she, sche, scheo, scho, AS. se['o], fem. of the definite article, originally a demonstrative pronoun; cf. OS. siu, D. zij, G. sie, OHG. siu, s[imac], si, Icel. s[=u], sj[=a], Goth. si she, s[=o], fem. article, Russ. siia, fem., this, Gr. ?, fem. article, Skr. s[=a], sy[=a]. The possessive her or hers, and the objective her, are from a different root. See Her.]
1. This or that female; the woman understood or referred to; the animal of the female sex, or object personified as feminine, which was spoken of. [1913 Webster]
She loved her children best in every wise. --Chaucer. [1913 Webster]
Then Sarah denied, . . . for she was afraid. --Gen. xviii. 15. [1913 Webster]
2. A woman; a female; -- used substantively. [R.] [1913 Webster]
Lady, you are the cruelest she alive. --Shak. [1913 Webster]
Note: She is used in composition with nouns of common gender, for female, to denote an animal of the female sex; as, a she-bear; a she-cat. [1913 Webster]