Noun
Half a tone; -- the name commonly applied to the smaller intervals of the diatonic scale.
Source: Webster's dictionaryYou knew exactly who the good guys were and who were the bad guys just by the chord: the good guys got a perfect fifth - strong, compassionate - the bad guys got an augmented fourth... Just a semitone, but sometimes in life when you make the wrong choices, it's just a semitone out. Bill Bailey
A 4 in particular, which is at the seventh partial (sixth overtone) is nearly always 31 cents, or about one third of a semitone, flat of the minor seventh. Source: Internet
Adding a double accidental (double sharp) to F in this case only raisees F by one further semitone, creating G natural. Source: Internet
Additionally, it also makes the semitone exactly half a whole tone, the simplest possible relationship. Source: Internet
Alternatively, a cross placed next to a number indicates that the pitch of that note should be raised by a semitone (so that if it is normally a flat it becomes a natural, and if it is normally a natural it becomes a sharp ). Source: Internet
A sharp symbol on a line or space in the key signature raises the notes on that line or space one semitone above the natural, and a flat lowers such notes one semitone. Source: Internet