Definition and background:
A fast tempo marking between Allegretto and Vivace. A composition in fast tempo, especially the first and last movements of a sonata, symphony, etc. Italian. A fast tempo. In Italian the word means lively or merry. fast and lively, but not as fast as presto
Fast, lively; an indication of tempo used as a playing direction in music.
Italian. A fast tempo. In Italian the word means lively or merry
For more information on the music term "Allegro" check out these other resources:
Wikipedia - Glossary of Musical Terminology
Virginia Tech Multimedia Music Dictionary
ORB -- Medieval Music Glossary