abundance has 2 distinct synonyms spread across 1 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 scarcity.
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 a more than adequate quantity or supply
“an age of abundance”
(physics) the ratio of the number of atoms of a specific isotope of an element to the total number of isotopes present
(chemistry) the ratio of the total mass of an element in the earth's crust to the total mass of the earth's crust; expressed as a percentage or in parts per million
Synonyms, antonyms and the broader and narrower relations for abundance come from Princeton University’s WordNet. Full sources and licences.