Sis

noun

1. A daughter of the same parents as another person; a female sibling.

   "My sister is always driving me crazy."

2. A female member of a religious order; especially one devoted to more active service; (informally) a nun.

   "Michelle left behind her bank job and became a sister at the local convent."

3. Any butterfly in the genus Adelpha, so named for the resemblance of the dark-colored wings to the black habit traditionally worn by nuns.
4. A senior or supervisory nurse, often in a hospital.
5. Any woman or girl with whom a bond is felt through common membership of a race, profession, religion or organization, such as feminism.

   "Connie was very close to her friend Judy and considered her to be her sister."