themselves

Etymology

Morphologically them + -selves.

pron

1. (reflexive) The reflexive case of they, the third-person plural personal pronoun. The group of people, animals, or objects previously mentioned, as the object of a verb or following a preposition (also used for emphasis).
   They’ve hurt themselves. (reflexively)
   They fought among themselves. (after a preposition)
   They are going to try climbing Mount Everest themselves. (for emphasis)
2. (reflexive) The reflexive case of they, the third-person singular personal pronoun. The single person previously mentioned, as the object of a verb or following a preposition (also used for emphasis).
   Would whoever stole my phone please make themselves known. (reflexively)
   I don't want anyone to fight among themselves. (after a preposition)
   Everyone must do it themselves. (for emphasis)
   In fact she was so busy doing all the things that anyone might, who finds themselves alone in an empty house, that she did not notice at first when it began to turn dusk and the rooms to grow dim. 1967, Barbara Sleigh, Jessamy, Sevenoaks, Kent: Bloomsbury, published 1993, page 18