A "straight ally".
Used in some Gay-
Straight Alliances and similar organizations to describe
people who are not LGBT, but who want to promote LGBT
rights, protect LGBT's from bullying, and/or simply want to reach out to a person who is LGB or T and let him/her know that s/he is in a safe place.
My best friend is a
transsexual and the
world views her as an abomination. That's one reason I'm a strally.
When I told my
mom I was a strally in my university's GSA, she thought that a strally was a new kind of lesbian.