Webster's Revised Unabridged Dictionary · 1913

Opaque

Opaque , adjective

[French, from Latin opacus. Compare Opacous.]

1.
Impervious to the rays of light; not transparent; as, an opaque substance.
2.
Obscure; not clear; unintelligible. [Colloquial]

Opaque , noun

That which is opaque; opacity. — Young