the quality of being unchanging or unwavering, as in purpose, love, or loyalty; firmness of mind; faithfulness.

uniformity or regularity, as in qualities or conditions; invariableness.

noun

change , changeableness , fluctuation , inconstancy , instability , irregularity , unsteadiness

noun

abidingness , adherence , allegiance , ardor , attachment , certainty , decision , dependability , determination , devotedness , devotion , doggedness , eagerness , earnestness , endurance , faith , fealty , fidelity , firmness , honesty , honor , integrity , love , loyalty , permanence , perseverance , principle , regularity , resolution , stability , staunchness , steadfastness , steadiness , surety , tenacity , trustiness , trustworthiness , truthfulness , unchangeableness , unfailingness , uniformity , zeal , faithfulness , fixedness , fortitude