al ‧ leg ‧ ro /əˈleɡrəʊ, əˈleɪ- $ -ɡroʊ/ BrE AmE noun ( plural allegros ) [countable]
[ Date: 1600-1700 ; Language: Italian ; Origin: 'cheerfully' , from Latin alacer ; ⇨ ↑ alacrity ]
a piece of music played or sung quickly
—allegro adjective , adverb