n. (UK, Ireland, Australia, New Zealand) The musical interval equal (exactly or approximately) to half a tone or one-twelfth of an octave
n. (UK, Ireland, Australia, New Zealand) Any of the pitches of the chromatic scale
the GNU version of the Collaborative International Dictionary of English
n. Half a tone; -- the name commonly applied to the smaller intervals of the diatonic scale.
The Century Dictionary and Cyclopedia
n. In music, an interval approximately equal to half of a tone; a minor second; a half-step.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. the musical interval between adjacent keys on a keyboard instrument
Word Usage
"Because the music has been made "bitonal" by moving the accompanying piano part up two semitones (a semitone is the difference between a "natural" note and a sharp or flat)."