What does sisters' mean?

Female relative sharing at least one biological or legal parent with subject. (ex. This is my sister, Lisa.)

A nun. (ex. I'd like you to meet Sister Marie Bernadette.)

Slang term for an African-American woman. Also seen written "sista". (ex. Halle Barry is a sister.) [Yeah, lame example. Somebody want to fix it?]

Slang term for a female with shared history with subject (e.g. religious community, social movement). (ex. Let us welcomeSister Janie Smith to our congregation.)