noun.
The quality of being invariable; invariableness; constancy; uniformity.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
a quality of uniformity and lack of variation
noun.
the quality of being resistant to variation
Word Usage
"In his early years, Linnaeus believed that the species was not only real, but unchangeable — as he wrote, Unitas in omni specie ordinem ducit (The invariability of species is the condition for order [in nature])."