Leo I

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

• Pope (440–461). His negotiations with Attila (452) and Genseric the Vandal (455) helped prevent the sacking of Rome.

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

• noun Italian pope from 440 to 461 who extended the authority of the papacy to the west and persuaded Attila not to attack Rome (440-461)