U

opaque

adjective

not transparent or translucent; impenetrable to light; not allowing light to pass through.
not transmitting radiation, sound, heat, etc.
not shining or bright; dark; dull.
hard to understand; not clear or lucid; obscure: The problem remains opaque despite explanations.
dull, stupid, or unintelligent.

noun

something that is opaque.
Photography. a coloring matter, usually black or red, used to render part of a negative opaque.

verb (used with object), o·paqued, o·paqu·ing.

Photography. to cover up blemishes on (a negative), especially for making a printing plate.
to cause to become opaque.

adjective

not transmitting light; not transparent or translucent
not reflecting light; lacking lustre or shine; dull
not transmitting radiant energy, such as electromagnetic or corpuscular radiation, or sound
hard to understand; unintelligible
unintelligent; dense

noun

photog an opaque pigment used to block out particular areas on a negative

verb opaques, opaquing or opaqued (tr)

to make opaque
photog to block out particular areas, such as blemishes, on (a negative), using an opaque

adj.early 15c., opake, from Latin opacus “shaded, in the shade, shady, dark, darkened, obscure,” of unknown origin. Spelling influenced after c.1650 by French opaque (c.1500), from the Latin. Figurative use from 1761. Related: Opaquely; opaqueness. adj.

Impenetrable by light; neither transparent nor translucent.

Resistant to the transmission of certain kinds of radiation, usually light. Metals and many minerals are opaque to light, while being transparent to radio waves and neutrinos. Compare translucent transparent.