It's a Latin noun, derived from an adjective, that literally means "a something of some size." That's it. The first meaning in English is "some quantity." Uses

It's a Latin noun, derived from an adjective, that literally means "a something of some size." That's it. The first meaning in English is "some quantity." Uses which denote or connote 'large' or 'small' are secondary extensions which depend on context. "Quantum leap" connotes an unpredictability in the magnitude of the change in common usage. Over time, the understanding has drifted a bit to include, usually, the idea of significant magnitude.