opaque

/əʊˈpeɪk/noun

A dark area or region where no light passes through.

Example sentence

“Beyond the reach of the lamplight, the cave dissolved into an opaque.”

Mostly an adjective: opaque glass, or opaque prose that resists understanding. Its opposite is 'transparent'.

Related words

opponentA person who competes against you or takes the opposite side, and tries to stop you from succeeding.onionA round vegetable of the garlic family, made of strong-smelling layers, eaten cooked or raw and used to flavour food.optimismThe habit of expecting things to go well or turn out for the best.onerousRequiring so much effort that it feels like a heavy load; hard to bear.optimistSomeone who believes things will turn out well.ominousSuggesting that something bad is about to happen; acting as a warning sign.