[1] : The Collaborative International Dictionary of English v.0.48

alla breve \al`la bre"ve\ it., according to the breve. old
   church music
   with one breve, or four minims, to measure, and sung faster
   like four crotchets; in quick common time; -- indicated in
   the time signature by ?.
   1913 webster

[2] : WordNet (r) 2.0

alla breve
     n : a musical time signature indicating two or four half notes
         to a measure

Alla Breve >> A Words
Alla Breve, definition of term: Alla Breve
alla+breve_pag1.html

Breve >> B Words
Breve, definition of term: Breve
breve_pag1.html