amplitude

noun

1. The measure of something's size, especially in terms of width or breadth; largeness, magnitude.
2. The maximum absolute value of the vertical component of a curve or function, especially one that is periodic.
3. The maximum absolute value of some quantity that varies.
4. The arc of the horizon between the true east or west point and the center of the sun, or a star, at its rising or setting. At the rising, the amplitude is eastern or ortive: at the setting, it is western, occiduous, or occasive. It is also northern or southern, when north or south of the equator.