New American Oxford Dictionary
themself
them self |T͟Həmˈself, T͟Hem -ðəmˈsɛlf | ▶pronoun [ third person singular ] used instead of “himself ” or “herself ” to refer to a person of unspecified sex: the casual observer might easily think themself back in 1945. usage: 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 usage at they .
Oxford Dictionary
themself
them |self |ð (ə )mˈsɛlf | ▶pronoun [ third person singular ] used instead of ‘himself ’ or ‘herself ’ to refer to a person of unspecified sex: the casual observer might easily think themself back in 1945. usage: 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 usage at they .
Sanseido Wisdom Dictionary
themself
them self /ð (ə )msélf /代名詞 ⦅話 非標準 ⦆=themselves (!性がはっきりしないときにhimselfやherselfを避けるために用いる ) .