Meaning of Greek-letter fraternity

Greek'-let•ter frater'nity

Pronunciation: (grēk'let"ur), [key]
  1. a fraternity whose name consists usually of two or three Greek letters, as Sigma Delta Phi (&Sgr;&Dgr;&PHgr;).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.