sis·ter ( P ) Pronunciation Key (sstr)
-A female having the same parents as another or one parent in common with another.
-A girl or woman who shares a common ancestry, allegiance, character, or purpose with another or others, specifically:
-A kinswoman.
-A woman fellow member, as of a sorority.
-A fellow woman.
-A close woman friend or companion.
-A fellow African-American woman or girl.
-A woman who advocates, fosters, or takes part in the feminist movement.

sib·ling ( P ) Pronunciation Key (sblng)
-One of two or more individuals having one or both parents in common; a brother or sister.

friend ( P ) Pronunciation Key (frnd)

-A person whom one knows, likes, and trusts.
-A person whom one knows; an acquaintance.
-A person with whom one is allied in a struggle or cause; a comrade.
-One who supports, sympathizes with, or patronizes a group, cause, or movement: friends of the clean air movement.
-Friend A member of the Society of Friends; a Quaker.