It is distorted in the sense that a sine wave that has been put through a nonlinear process -- e.g. clipped to form a square wave; clipped and integrated to form a triangle; clipped and integrated asymmetrically to form a saw; etc.
Total harmonic distortion measures the amount of power that you have in harmonics vs. the fundamental wave. A purely sinusoidal tone would have no energy in harmonics; a saw would have 44% of its energy in harmonics.
Maybe you're nitpicking and saying that it's not "distortion", but harmonic distortion as a metric of how much energy is in harmonics-- because the primary way we used to get those harmonics is by distortion of a sine wave-- is common lingo.
Maybe I was nitpicking about the use of the term "distortion" (I prefer "transformation"), but I did want to clarify that saw waves are more harmonically rich and complex than square waves.
Total harmonic distortion measures the amount of power that you have in harmonics vs. the fundamental wave. A purely sinusoidal tone would have no energy in harmonics; a saw would have 44% of its energy in harmonics.
Maybe you're nitpicking and saying that it's not "distortion", but harmonic distortion as a metric of how much energy is in harmonics-- because the primary way we used to get those harmonics is by distortion of a sine wave-- is common lingo.