opaque

/oʊˈpeɪk/

/əʊˈpeɪk/

Other forms: opaquer

Use the adjective opaque either for something that doesn't allow light to pass through (like a heavy curtain) or for something difficult to understand (like bureaucratic gobbledygook).

Opaque is from a Latin word meaning "dark," and that was its original sense in English, but it now means literally "not transparent" or metaphorically "hard to understand; unclear": "Some of his sentences are really opaque." It used to be spelled opake, which made the pronunciation clearer, but we then borrowed the more opaque French spelling. Come to think of it, English spelling is often pretty opaque, which makes it hard for learners of the language to master.

Definitions of opaque

1. adjective

   not transmitting or reflecting light or radiant energy; impenetrable to sight
   “opaque windows of the jail”

   “opaque to X-rays”

   synonyms:

   unclear

   not clear to the mind

   cloudy, mirky, muddy, murky, turbid

   (of liquids) clouded as with sediment

   fogged, foggy

   obscured by fog

   frosted

   (of glass) having a roughened coating resembling frost

   glaucous

   having a frosted look from a powdery coating, as on plants

   light-tight, lightproof

   not penetrable by light

   milklike, milky, whitish

   resembling milk in color not clear

   semiopaque

   partially opaque

   solid

   impenetrable for the eye

   antonyms:

   clear

   allowing light to pass through

   crystal clear, crystalline, limpid, lucid, pellucid, transparent

   transmitting light; able to be seen through with clarity

   hyaline, hyaloid

   resembling glass in transparency or translucency

   limpid, liquid

   clear and bright

   semitransparent, translucent

   allowing light to pass through diffusely

   unclouded

   not made opaque or cloudy by sediment

   unfrosted

   (of glass) lacking a frosted coating
2. adjective

   not clearly understood or expressed
   synonyms: unintelligible

   incomprehensible, uncomprehensible

   difficult to understand