ONESELF
Etymology
Pronoun
oneself (reflexive form of the indefinite personal pronoun one, formerly sometimes two words: one's self)
A person's self: general form of himself, herself or yourself.
Usage notes
This pronoun can be used for emphasis or to make a verb reflexive.
Synonyms
• one's self
Source: Wiktionary
One`self", pron.
Definition: A reflexive form of the indefinite pronoun one. Commonly writen
as two words, one's self.
One's self (or more properly oneself), is quite a modern form. In
Elizabethan English we find a man's self=one's self. Morris.
Source: Webster’s Unabridged Dictionary 1913 Edition