Nouns

(n)mattea mixture of sulfides that forms when sulfide metal ores are smelted
(n)flatness, lusterlessness, lustrelessness, mat, matt, mattethe property of having little or no contrast; lacking highlights or gloss

Verbs

(v)felt, felt up, mat up, matt-up, matte up, matte, matchange texture so as to become matted and felt-like“The fabric felted up after several washes”

Adjectives

(s)flat, mat, matt, matte, mattednot reflecting light; not glossy“flat wall paint”, “a photograph with a matte finish”