Definitions by BabsCatfish

Significant brother 

A man married to his sibling/step-sibling.

Pam: did you hear Brittany got married? I wonder who the groom is...
Karen: oh, she married her step brother. Such a good love story, when one finds romance with their significant brother.

(Cue banjos)

Significant brother by BabsCatfish August 2, 2019