Intonation is accuracy of pitch in playing or singing; in other words, being neither sharp (too high) or flat (too low). A singer with good intonation sings 'in tune'.

 

With a fretless string instrument, such as a violin, intonation depends on the musician pressing with his or her finger at the exact spot on the instrument's fingerboard.

 

To intone is to produce a tone, thus the term was used in plainchant to indicate the initial melodic statement sung before all the voices enter.