Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

aplanatic

adjective ap·la·nat·ic \ ˌa-plə-ˈna-tik \
See What's Trending Now See More Trending Words

Definition of aplanatic

: free from or corrected for spherical aberration
  • an aplanatic lens

Origin and Etymology of aplanatic

a- + Greek planasthai to wander — more at planet

Medical Dictionary

aplanatic

adjective ap·la·nat·ic \ ˌap-lə-ˈnat-ik, ˌā-plə- \

medical Definition of aplanatic

: free from or corrected for spherical aberration
  • an aplanatic lens
—

aplanatically

play \-i-k(ə-)lē\ adverb

Seen and Heard

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

show hide

Love words? Need even more definitions?

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

WORD OF THE DAY

grudging

play

unwilling or reluctant

Get Word of the Day daily email!

TRENDING NOW

  1. lowlife 'a person of low moral character'

  2. kakistocracy 'government by the worst people'

  3. slimeball 'a morally repulsive or odious person'

  4. salacious 'arousing or appealing to sexual desire'

  5. oligarch 'government in which a small group exercises control'

SEE ALL

BROWSE DICTIONARY

aplanatic

Test Your Vocabulary

Odd Habits and Quirks Quiz

  • image1926873504
  • Which of the following best describes an easily irritated person?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Word Winder's CrossWinder

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

image236659401
Words from Letters in the Greek Alphabet

When English borrows from another alphabet

alt-5ada140ed3e28
'Preventive' or 'Preventative'?

Why not both?

alt-5ad8fc71357ed
Words We're Watching: 'Bluebeard,' the Verb

No, it's not a coiffure trend

alt-5ad8d3361fb97
Where 'Cliff-hangers' Come From

You're on the edge of your seat

Ask the Editors

image1760257654
2017 Word of the Year: Behind the Scenes

How we chose 'feminism'

video-title-words-of-the-year-1066
Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

video-literally
Literally

How to use a word that (literally) drives some people nuts.

video-his-or-her
Is Singular 'They' a Better Choice?

The awkward case of 'his or her'

Word Games

image1926873504
Odd Habits and Quirks Quiz

Test your knowledge of strange human behaviors.

Take the quiz
cats-on-impossible-timber
More Confusing Words—Quiz

How many of these commonly confused words do you know?

Take the quiz
Spell It
Spell It

Can you spell these 10 commonly misspelled words?

Take the quiz
Word Winder's CrossWinder
Word Winder's CrossWinder

A game of winding words.

Play the game