Merriam-Webster Logo
SINCE 1828
dictionary thesaurus view recents

photonasty

noun
Save Word
pho·​to·​nas·​ty
plural -es

Definition of photonasty

: a nastic movement that is associated with changes in light intensity

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!

History and Etymology for photonasty

International Scientific Vocabulary phot- + -nasty; probably originally formed as German photonastie

Keep scrolling for more

Learn More about photonasty

Statistics for photonasty

Cite this Entry

“Photonasty.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/photonasty. Accessed 13 December 2019.

Comments on photonasty

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

Show Comments  Hide Comments 

WORD OF THE DAY

tractable

Listen to the pronounciation of tractable

easily led, controlled, or managed

Get Word of the Day daily email!

Test Your Vocabulary

Semantic Drift Quiz

  • a twisty river
  • Which of the following was once a synonym for fun?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Dictionary Devil

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