time signature

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

• noun A sign placed on a staff to indicate the meter, commonly a numerical fraction of which the numerator is the number of beats per measure and the denominator represents the kind of note getting one beat.

from The Century Dictionary.

• noun In musical notation, same as rhythmical signature (which see, under rhythmical).

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

• (Music) A sign at the beginning of a composition or movement, placed after the key signature, to indicate its time or meter. Also called rhythmical signature. It is in the form of a fraction, of which the denominator indicates the kind of note taken as time unit for the beat, and the numerator, the number of these to the measure.

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

• noun music A numerical sign placed on a stave to indicate the meter; the numerator is the number of beats per bar, the denominator represents the value of each beat

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

• noun a musical notation indicating the number of beats to a measure and kind of note that takes a beat