Wordnet 3.0
NOUN (1)
1.
a musical time signature indicating two or four half notes to a measure;
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]
WordNet (r) 3.0 (2006):
alla breve
n 1: a musical time signature indicating two or four half notes
to a measure