With reference to its spotted coat, as a type of unchangeableness, after Jeremiah xiii. 23.

In proverbs and proverbial phrases. the law of the Medes and Persians, often used (with allusion to Dan. vi. 12) as the type of something unalterable.

Mathematics and Physics. A quantity which does not vary, or which is assumed not to vary, throughout an investigation: opposed to variable.

In form hard core. A central or fundamental element which cannot be removed or reduced; an intractable person, group, or thing.

gen. The property of remaining unaltered or of being the same in different circumstances; an instance of this, an invariant.

gen. An invariant property or feature.

An instance of this property; an unchangeable fact, a given.