matrix has 2 distinct synonyms spread across 1 of its 6 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
(mathematics) a rectangular array of quantities or expressions set out by rows and columns; treated as a single element and manipulated according to rules
Synonyms, antonyms and the broader and narrower relations for matrix come from Princeton University’s WordNet. Full sources and licences.
(geology) a mass of fine-grained rock in which fossils, crystals, or gems are embedded
an enclosure within which something originates or develops (from the Latin for womb)
the body substance in which tissue cells are embedded
the formative tissue at the base of a nail
mold used in the production of phonograph records, type, or other relief surface