brother vs co-parent

brother

noun
  • Son of the same parents as another person. 

  • A form of address to a man. 

  • Someone who is a peer, whether male or female. 

  • A male fellow member of a religious community, church, trades union etc. 

  • A male having at least one parent in common with another (see half-brother, stepbrother). 

  • Somebody, usually male, connected by a common cause, situation, or affection. 

  • A black male. 

  • Someone who is a kinsman or shares the same patriarch. 

verb
  • To treat as a brother. 

intj
  • Expressing exasperation. 

co-parent

noun
  • A parent in a same-sex couple. 

  • A godparent. 

  • A divorced or separated parent who shares custody with the other parent. 

  • Someone who shares in the parenting of a child or children, such as 

verb
  • To act as a co-parent; to share custody of a child or children; to share in the responsibility of parenting a child or children. 

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