themself
Pronunciation: /ð(ə)mˈsɛlf/
pronoun

The standard reflexive form corresponding to they and them is themselves, as in they can do it themselves. The singular form themself, first recorded in the 14th century, has re-emerged in recent years corresponding to the singular gender-neutral use of they, as in this is the first step in helping someone to help themself. The form is not widely accepted in standard English, however. For more details, see they (usage).