1) Alone, when preceded by by 2) Personal identity 3) Word after be or by 1) Ego 2) Id 3) Identity 4) Numero uno 
• (pron.) A reflexive form of the indefinite pronoun one. Commonly writen as two words, one`s self.
One`self' pron. 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.