The belief or assumption that everyone is, or should be heterosexual; the idea that being heterosexual is normal, natural and healthy, and all other people are somehow unnatural, abnormal and unhealthy.

Ball State University. (n.d.). Safe zone training (PDF). Retrieved from https://cms.bsu.edu/-/media/WWW/DepartmentalContent/CounselingCenter/PDFs/SafeZone-Participant%20Manual%20-%20Full%20Version%20- May%202012.pdf.