consistency has 3 distinct synonyms spread across 2 of its 4 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is inconsistency.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the property of holding together and retaining its shape
“wool has more body than rayon”
a harmonious uniformity or agreement among things or parts
logical coherence and accordance with the facts
“a rambling argument that lacked any consistency”
(logic) an attribute of a logical system that is so constituted that none of the propositions deducible from the axioms contradict one another
Synonyms, antonyms and the broader and narrower relations for consistency come from Princeton University’s WordNet. Full sources and licences.