Definition of phototropism
: a tropism in which light is the orienting stimulus
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
Slippery Words Quiz—Changing with the Times
- What is an earlier meaning of nice?

Test your vocabulary with our 10-question quiz!
TAKE THE QUIZ
Spell words. Make bears.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
Slippery Words Quiz—Changing with the Times
Do you know these earlier meanings of words?
Take the quizWords of Snow and Ice Quiz
A selection of words from the chillier parts of t...
Take the quizHow Strong Is Your Vocabulary?
Test your vocabulary with our 10-question quiz!
Take the quizPlay the game
Share phototropism
Time Traveler for phototropism
The first known use of phototropism was in 1899
See more words from the same year