Brotherboy and Sistergirl

Sistergirl (Sistagirl) and Brotherboy (Brothaboy) are genders from Australian Aboriginal and Torres Strait Islander cultures. The terms are not analogous to transfeminine and transmasculine as understood in the non-Indigenous LGBTA community, and were coined directly by Indigenous individuals.

Someone who describes themself as a sistergirl or brotherboy is understood to live their life through gendered experiences that aren't consistent with their assigned gender at birth. This includes gender identity but also cultural identity, social role, and other gendered aspects of the Indigenous cultural worldview. Because of this, the terms do not explicitly refer to those who may otherwise be described as transgender.

A sistergirl may be a transgender woman, a transfeminine non-binary individual, a feminine gay man, a drag queen, or any other permutation.

A brotherboy may a transgender man, a transmasculine non-binary individual, a masculine lesbian/sapphic individual, a drag king, or an otherwise butch individual.

Sistergirls and brotherboys may not consider themselves to identify as the gender the word may imply; one may be a sistergirl but not a woman.

Like many concepts of gender from Indigenous individuals, the Indigenous Australian concepts of gender, including sistergirls and brotherboys, is not best understood in terms of western gender-descriptive language, and should not be misunderstood as being a term for transgender individuals. Indigenous culture surrounding gender in so-called Australia was affected by white invasion which attempted to enforce gender role based on physicality rather than spirituality - based on body parts instead of internal gender experience. Indigenous culture around Australia varies and many sistergirls and brotherboys are subject to homophobia and transphobia in their communities, a significant deal of which is due to colonial enforcement of strict gender.

Note
"Indigenous" with a capital "I" is the correct way of referring to Indigenous Australians, as opposed to indigenous with no capitalization, which refers to native individuals in general.