Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

entrance pupil

noun

Definition of entrance pupil 

: the stop in an optical instrument or the virtual image of the stop that determines the angular diameter of the bundle of rays traversing the instrument from a given point in the object space — compare exit pupil

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Learn More about entrance pupil

Share entrance pupil

Resources for entrance pupil

Cite Time Traveler Time Traveler! Explore the year a word first appeared

Dictionary Entries near entrance pupil

entrance examination

entrance hall

entrance path

entrance pupil

entranceway

entrant

entrap

Statistics for entrance pupil

Look-up Popularity

Comments on entrance pupil

What made you want to look up entrance pupil? Please tell us where you read or heard it (including the quote, if possible).

Show Comments  Hide Comments 

WORD OF THE DAY

rebuff

to reject or criticize sharply

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

Ask the Editors

Word Games