The adjective opaque means something that prevents light from travelling through, and therefore not transparent or translucent.

Synonyms are clouded, muddy, thick, or impenetrable.

The word origins from late Middle English (early 15th century) opake meaning and from Latin opacus meaning “shaded, in the shade, shady, dark, darkened, obscure”. The current spelling has been influenced by the French (1500) opaque.

Please buy windows that can switch from opaque to clear.

Some crystals are opaque, while some are white and transparent.

From here, I can’t see what’s inside her opaque glass.