Impervious to the rays of light; not transparent; as, an opaque substance.
- Impenetrable by light; neither transparent nor translucent.
- Not reflecting light; having no luster: an opaque finish.
- Impenetrable by a form of radiant energy other than visible light: a chemical solution opaque to x-rays.
- So obscure as to be unintelligible: "opaque, elusive, minimal meanings” ( John Simon).
- Obtuse of mind; dense. See Synonyms at dark.
- Something that is opaque, especially an opaque pigment used to darken parts of a photographic print or negative.