ally

ally: aliado

this is an obvious one, but what may not be obvious is how the term gets used in movements in the US and Canada (and the UK?) to mean "people who recognize the unearned privilege they receive from society’s patterns of injustice and take responsibility for changing these patterns. Allies include men who work to end sexism, white people who work to end racism, heterosexual people who work to end heterosexism, able-bodied people who work to end ableism, and so on."

if you have a sense that your listeners or readers do not understand this movement use of the term, it is worth explaining.

(this definition of ally is from this article on tips for white allies in the occupy movement)