co vs zir

co

pron
  • them (singular). Gender-neutral object pronoun, coordinate with gendered pronouns him and her. 

  • they (singular). Gender-neutral subject pronoun, coordinate with gendered pronouns he and she. 

zir

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

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

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

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