from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. An instrument designed to measure the numerical aperture of a lens or objective of a microscope.

from The Century Dictionary and Cyclopedia

  • n. An instrument used to measure the angular aperture of the object-glass of a microscope.


Sorry, no etymologies found.


Sorry, no example sentences found.

Wordnik is becoming a not-for-profit! Read our announcement here.


Log in or sign up to get involved in the conversation. It's quick and easy.