their
det.det. belonging to or connected with a group of people, animals, or things that you have already mentioned. You use it to show that something is owned by them.
det. the possessive form of the third-person plural pronoun 'they', used to indicate ownership or association. It is also increasingly used as a gender-neutral singular possessive to refer to a person whose gender is unknown or irrelevant.
The children are playing with their new toys in the garden.
The neighbors asked if we could watch their dog while they are away on vacation next week.
While the committee members expressed diverse opinions during the debate, they eventually reached a consensus and submitted their final report to the board for review.
From Old Norse þeirra. Replaced native Old English heora.
A possessive determiner that must be followed by a noun or noun phrase.