Noun

(en noun)

The measure of something's size, especially in terms of width or breadth; largeness, magnitude.

* Fuller

The cathedral of Lincoln is a magnificent structure, proportionable to the amplitude of the diocese.

* Milton

amplitude of mind

* Macaulay

amplitude of comprehension

(mathematics) The maximum absolute value of the vertical component of a curve or function, especially one that is periodic.

(physics) The maximum absolute value of some quantity that varies.

(astronomy) 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.

(astronomy) The arc of the horizon between the true east or west point and the foot of the vertical circle passing through any star or object.

(firearms) The horizontal line which measures the distance to which a projectile is thrown; the range.

Noun

(wikipedia brightness) (en-noun)

The quality of being bright.

*, chapter=5

, title= The Mirror and the Lamp , passage=Here, in the transept and choir, where the service was being held, one was conscious every moment of an increasing brightness ; colours glowing vividly beneath the circular chandeliers, and the rows of small lights on the choristers' desks flashed and sparkled in front of the boys' faces, deep linen collars, and red neckbands.}}

The perception elicited by the luminance of an object.

Intelligence, cleverness.