sufficiency has 2 distinct synonyms spread across 2 of its 3 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 insufficiency.
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.
sufficient resources to provide comfort and meet obligations
“her father questioned the young suitor's sufficiency”
an adequate quantity; a quantity that is large enough to achieve a purpose
“enough is as good as a feast”
Synonyms, antonyms and the broader and narrower relations for sufficiency come from Princeton University’s WordNet. Full sources and licences.
the quality of being sufficient for the end in view
“he questioned the sufficiency of human intelligence”