What does the word optical mean?

Usage examples for optical

  1. In the laboratory, on the other hand, the place of the different instruments will be determined by a classification according to methods, such as weighing and measuring, observations of time, optical and electrical methods of observation, and so on. – Five of Maxwell's Papers by James Clerk Maxwell
  2. And yet- if that devilish rum optical delusion hadn't come off- why I should have dozed on comfortably, and never have heard that chump's shout for help. – The Heath Hover Mystery by Bertram Mitford
  3. I repeated the time- worn argument about optical illusions, etc. – Uncanny Tales by Mary Louisa Molesworth