they vs zir

they

pron
  • A single person, previously mentioned, but typically not if previously named and identified as male or female, especially if of unknown or (since 21st century) non-binary gender. 

  • There (especially as an expletive subject of be). 

  • People; some people; people in general; someone, excluding the speaker. 

  • A group of entities previously mentioned. 

det
  • Their. 

  • The, those. 

zir

pron
  • Gender-neutral third-person singular accusative (object) pronoun, equivalent to singular them and coordinate with him and her. 

det
  • Belonging to zir, gender-neutral third-person singular possessive adjective, equivalent to singular their and coordinate with his and her. 

noun
  • A large clay jug for storing water, common in Egypt and the Sudan since ancient times. 

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