Meanings
sister
Meine Schwester kommt morgen.My sister is coming tomorrow.
colloquialnurse; by extension used to refer to any medical staff that is not a doctor (usually, but not necessarily, confined to female staff)
nurse; used as a title of address for nurses
sister; nun; used particularly, but not only, as a title of address
sister; sis
Meine Schwester geht in die 8. Klasse.
Examples
GermanEnglish
Du bist so groß wie meine Schwester.You're as tall as my sister.
Du bist für mich wie eine Schwester.You're like a sister to me.