sister

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A female having the same parents as another or one parent in common with another.
• noun A girl or woman who shares a common ancestry, allegiance, character, or purpose with another or others, specifically.
• noun A kinswoman.
• noun A woman fellow member, as of a sorority.
• noun A fellow woman.
• noun A close woman friend or companion.
• noun A fellow African-American woman or girl.
• noun A woman who advocates, fosters, or takes part in the feminist movement.
• noun Informal Used as a form of address for a woman or girl.
• noun A member of a religious order of women; a nun.
• noun Used as a form of address for such a woman, alone or followed by the woman's name.
• noun Chiefly British A nurse, especially the head nurse in a ward.
• noun One identified as female and closely related to another.
• adjective Related by or as if by sisterhood; closely related.
• adjective Genetics Of or being one of an identical, related, or homologous pair.

from The Century Dictionary.

• noun A female person in her relation to other children born of the same parents; a female relative in the first degree of descent or mutual kinship; also, a female who has attained a corresponding relation to a family by marriage or adoption: correlative to brother; often used as a term of endearment.
• noun Metaphorically, a woman of one's own faith, church, or other religious community.
• noun In the Roman Catholic and some other churches, a member of a religious community or order of women; a woman who devotes herself to religious work as a vocation: as, sisters of mercy. See sisterhood, 2.
• noun That which is allied by resemblance or corresponds in some way to another or others, and is viewed as of feminine rather than masculine character.
• Standing in the relation of a sister, whether by birth, marriage, adoption, association, or resemblance; akin in any manner; related.
• To be a sister or as a sister to; resemble closely.
• To address or treat as a sister.
• To be a sister or as a sister; be allied or contiguous.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb obsolete To be sister to; to resemble closely.
• noun A female who has the same parents with another person, or who has one of them only. In the latter case, she is more definitely called a half sister. The correlative of brother.
• noun A woman who is closely allied to, or assocciated with, another person, as in the sdame faith, society, order, or community.
• noun One of the same kind, or of the same condition; -- generally used adjectively.
• noun (Naut.) a tackle block having two sheaves, one above the other.
• noun a pair of hooks fitted together, the shank of one forming a mousing for the other; -- called also match hook.
• noun (R. C. Ch.) See under Charity, and Mercy.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a daughter of the same parents as another person; a female sibling.
• noun a female member of a religious community; a nun.
• noun UK a senior or supervisory nurse, often in a hospital.
• noun any woman or girl with whom a bond is felt through common membership of a race, profession, religion or organization, such as feminism.
• noun slang a black woman
• noun informal a form of address to a woman
• noun a woman, in certain labour or socialist circles; also as a form of address.
• noun attributively Of or relating to an entity that has a special or affectionate, non-hierachical relationship with another.
• noun In the same class.
• verb transitive, construction To strengthen (a supporting beam) by fastening a second beam alongside it.
• verb obsolete, transitive To be sister to; to resemble closely.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (slang) sometimes used as a term of address for attractive young women
• noun a female person who is a fellow member of a sorority or labor union or other group
• noun (Roman Catholic Church) a title given to a nun (and used as a form of address)
• noun a female person who has the same parents as another person