#sharp sign
- Ais — A specialized technical term utilized in Western music theory that denotes the note A raised by a chromatic semitone using a sharp (A-sharp); it also represents the exact acoustic frequency or the corresponding key for this sound on keyboard instruments. Within structural and harmonic contexts, the word serves in solfeggio and composition as a component part of complex scales, chords, or melodic intervals, being enharmonically equivalent to the note B-flat, but possessing a completely different syntactic function within tonality.