An combined form of the devices 'his' and 'her' with the similar usage in referring to a subject (or
possessive, attributive) of both, either, or neither gender.
'Hir' and related nominative 'shi' are seen most often in internet-presented stories involving (the usually
pornographically inclined presence of) hermaphrodites or those capable of changing their sex with
ease.
Hir pillow was well
fluffed, to
hir pleasure.
We know hir well;
shi cannot surprise us any more.
He seemed perfectly alright with hir cutting him in line.