Definition of "opaque"

opaque

/əʊˈpeɪk/

adjective
comparative more opaque or opaquer, superlative most opaque or opaquest
1. Neither reflecting nor emitting light.
  Quotations
  We have agreed that heat is energy to begin with. Light is also a form of energy for when absorbed by any opaque substance it turns completely into heat.
  1968, Isaac Asimov, Photosynthesis, Basic Books, Inc., page 60
2. Allowing little light to pass through, not translucent or transparent.
3. (figuratively) Unclear, unintelligible, hard to get or explain the meaning of.
4. (figuratively) Obtuse, stupid.
5. (computing) Describes a type for which higher-level callers have no knowledge of data values or their representations; all operations are carried out by the type's defined abstract operators.
noun
plural opaques
1. (obsolete, poetic) An area of darkness; a place or region with no light.
  Quotations
  Through this opaque of Nature and of Soul, / This double night, transmit one pitying ray, / To lighten, and to cheer.
  1745, Edward Young, Night-Thoughts, section I
2. Something which is opaque rather than translucent.
verb
third-person singular simple present opaques, present participle opaquing, simple past and past participle opaqued
1. (transitive) To make, render (more) opaque.