1. Extent of dimensions; size; applied to things that have length, breath, and thickness. "Conceive those particles of bodies to be so disposed amongst
themselves, that the intervals of empty
spaces between them may be equal
to them all." (Sir I. Newton)
2. That which has one or more of the three dimensions, length, breadth, and thickness.
3. Anything of which greater or smaller can be predicated, as time, weight, force, and the like.
4. Greatness; grandeur. "With plain, heroic magnitude of mind."
5. Greatness, in reference to influence or effect; meaning; as, an affair of magnitude. "The magnitude of his designs." (Bp.
Horsley) Apparent magnitude, the angular breadth of an object viewed as measured by the angle which it subtends at the eye of the observer; called also apparent diameter.
Magnitude of a star, the rank of a star with respect to brightness. About twenty very bright stars are said to be of first magnitude, the stars of the sixth magnitude being just visible to the naked eye. Telescopic stars are classified down to the twelfth magnitude or lower. The scale of the magnitudes is quite arbitrary, but by means of photometers, the classification has been made to tenths of a magnitude.
Origin: L. Magnitudo, from magnus great. See Master, and cf. Maxim.
Source: Websters Vocabulary