he vs theirs

he

pron
  • they; he or she (a person whose gender is unknown or irrelevant.) 

  • A genderless object regarded as masculine, such as certain stars or planets (e.g. Sun, Mercury, Mars, Jupiter) or certain ships. 

  • A male person or animal already known or implied. 

  • it; an animal whose gender is unknown. 

noun
  • A male. 

  • The name of the first letter of the Old South Arabian abjad. 

  • The name of the fifth letter of many Semitic alphabets (Phoenician, Aramaic, Hebrew, Syriac, Arabic and others). 

  • The game of tag, or it, in which the player attempting to catch the others is called "he". 

  • The player who chases and attempts to catch the others in this game. 

det
  • Synonym of his 

intj
  • An expression of laughter. 

theirs

pron
  • That which belongs to them; the possessive case of they, used without a following noun. 

How often have the words he and theirs occurred in a corpus of books? (source: Google Ngram Viewer )