Final answer:
A sound with a definite pitch in music is called a tone, distinguished from noise, and different from timbre, which portrays a sound's unique characteristics despite having the same pitch and loudness.
Step-by-step explanation:
In music, a sound that has a definite pitch is referred to as a tone. Pitch is the perception of the frequency of a sound, and it is the quality that allows us to classify a sound as musical note. A sound at a particular pitch can be represented by names like A-sharp, C, or E-flat in Western music. For example, the ability to identify such musical notes by ear is termed perfect pitch, which is a rare skill. A tone is distinct from noise, which lacks a definite pitch, and it is also different from the loudness of sound, which can be described in terms of intensity level or decibels. Furthermore, timbre is the quality of a tone that distinguishes different sounds from one another, even if they have the same pitch and loudness, due to the complex interplay of frequency, amplitude, and timing of the sound waves.