1. the imperial guard created in 1804 by Napoleon: it made the last French charge at Waterloo.
2. (in the U.S.) the conservative element of any political party, esp. the Republican party.
3. (usually l.c.) the influential, established, more conservative members of any body, group, movement, etc.: the old guard of New York society.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.