Definition of "allegro"

allegro

/əˈlɛɡɹoʊ/

noun
plural allegros
1. (music) A tempo mark directing that a passage is to be played in a quick, lively tempo, faster than allegretto but slower than presto.
2. (music, more, traditionally) An expressive mark indicating that a passage is to be played in a lively or happy manner, not necessarily quickly.
3. (music) A passage having this mark.
  Quotations
  And what mean these outbursts and objurgations of his, you will ask; these suggestions, furtive, rhapsodical, mystical; this furibund allegro about Money, Mediums, and Bohemia; [...]
  1910 January 12, Ameen Rihani, “Subtranscendental”, in The Book of Khalid, New York, N.Y.: Dodd, Mead and Company, published October 1911, book the second (In the Temple), page 116
adverb
not comparable
1. (music) played in a quick, lively tempo
adjective
not comparable
1. (music) in a quick and lively manner