sister

Etymology

PIE word *swésōr From Middle English sister, suster, from Old English swustor, sweoster, sweostor (“sister, nun”); from Proto-Germanic *swestēr (“sister”), from Proto-Indo-European *swésōr (“sister”). Cognate with Scots sister, syster (“sister”), West Frisian sus, suster (“sister”), Dutch zuster (“sister”), German Schwester (“sister”), Norwegian Bokmål søster (“sister”), Norwegian Nynorsk and Swedish syster (“sister”), Icelandic systir (“sister”), Gothic 𐍃𐍅𐌹𐍃𐍄𐌰𐍂 (swistar, “sister”), Latin soror (“sister”), Russian сестра́ (sestrá, “sister”), Lithuanian sesuo (“sister”), Albanian vajzë (“girl, maiden”), Sanskrit स्वसृ (svásṛ, “sister”), Persian خواهر (xâhar, “sister”). In standard English, the form with i is due to contamination with Old Norse systir (“sister”). The plural sistren is from Middle English sistren, a variant plural of sister, suster (“sister”); compare brethren.

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; (informal) 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. (Britain) A senior or supervisory nurse, often in a hospital.
5. Any woman or girl with whom a bond is felt through common membership in a community, race, profession, religion, organization, or ism.
   Connie was very close to her friend Judy and considered her to be her sister.
   Sisters are doing it for themselves / Standing on their own two feet 1985, “Sisters Are Doin’ It for Themselves”, in Who’s Zoomin' Who?, performed by Eurythmics and Aretha Franklin
6. (African-American Vernacular, slang, sometimes capitalized) A black woman.
   The short “naps” of the average Sister do not sway in the wind as that of a blonde. 2009, Rajen Persaud, Why Black Men Love White Women, Simon and Schuster, page 171
   And now, social media has made it worse. From Facebook to Twitter, I get all kinds of invitations. Recently a sister inboxed me on Facebook and told me that she knew for a fact that I wanted her and she wanted me. 2014, J. L. King, Full Circle: Loving. Living. Life. After The Down Low
7. (informal) A form of address to a woman.
   What’s up, sister?
   "Listen, sister. I've got a job for you." 1932, Delos W. Lovelace, King Kong, published 1965, page 13
8. A woman, in certain religious, labour or socialist circles; also as a form of address.
   Thank you, sister. I would like to thank the sister who just spoke.
9. (attributively) An entity that has a special or affectionate, non-hierarchical relationship with another.
   sister publication
   sister city
   sister projects
10. (computing theory) A node in a data structure that shares its parent with another node.
11. (usually attributively) Something in the same class.
    sister ships
    sister facility

verb

1. (transitive, construction) To strengthen (a supporting beam) by fastening a second beam alongside it.
   I’m trying to correct my sagging floor by sistering the joists.
2. (obsolete, transitive) To be sister to; to resemble closely.