n. Greatness; vastness, whether in a physical or a moral sense; grandeur.n. Largeness of relation or significance; importance; consequence: as, in affairs of magnitude disdain not to take counsel.n. Size, or the property of having size; the extended quantity of a line, surface, or solid; length, area, or volume.n. Any kind of continuous quantity which is comparable with extended quantity.n. In astronomy, the brightness of a star expressed according to the numerical system used by astronomers for that purpose.n. In ancient prosody, the length of a syllable, foot, colon, or meter, expressed in terms of the metrical unit (primary time, semeion, or mora): as, a foot of trisemic magnitude; a colon of icosasemic magnitude.