blackboard

From black +‎ board, because such surfaces were once typically made of black slate.

• (General American) IPA^(key): /ˈblækbɔɹd/, /ˈblækboɹd/
• (Received Pronunciation) IPA^(key): /ˈblækbɔːd/

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• Rhymes: -ækbɔː(ɹ)d, -ækboɹd
• Hyphenation: black‧board

blackboard (plural blackboards)

Physicist Paul Dirac at the blackboard.

1. A large flat surface, finished with black slate or a similar material, that can be written upon with chalk and subsequently erased; a chalkboard.
   • 2012 March, Brian Hayes, “Pixels or Perish”, in American Scientist‎, volume 100, number 2, archived from the original on 19 February 2013, page 106:

     Drawings and pictures are more than mere ornaments in scientific discourse. Blackboard sketches, geological maps, diagrams of molecular structure, astronomical photographs, MRI images, the many varieties of statistical charts and graphs: These pictorial devices are indispensable tools for presenting evidence, for explaining a theory, for telling a story.

• writing board

• blackboard bold

• chalkboard
• greenboard
• whiteboard

blackboard (third-person singular simple present blackboards, present participle blackboarding, simple past and past participle blackboarded)

1. To use a blackboard to assist in an informal discussion.