alla breve

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adverb & adjective In cut time.
• noun The sign indicating that a passage is to be played in cut time.

from The Century Dictionary.

• In music, an expression understood to denote— a species of time in which every bar contains a breve, or four minims; or a rhythm of two or four beats to a bar, but taken at a rate of movement twice as fast as if the piece were simply marked with the sign of common time. The sign for alla breve time is .

from the GNU version of the Collaborative International Dictionary of English.

• (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 �.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun music a time signature when the half note is the beat and there are two beats per measure

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a musical time signature indicating two or four half notes to a measure