phototaxis

noun

pho·​to·​tax·​is ˌfō-tō-ˈtak-səs How to pronounce phototaxis (audio)
: a taxis in which light is the directive factor

Word History

Etymology

New Latin

First Known Use

circa 1889, in the meaning defined above

Time Traveler
The first known use of phototaxis was circa 1889

Rhymes for phototaxis

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Browse Nearby Words

phototactic
phototaxis
phototelegraph
See all Nearby Words

Cite this Entry

“Phototaxis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/phototaxis. Accessed 7 Jul. 2026.

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Kids Definition

phototaxis

noun
pho·​to·​tax·​is ˌfōt-ō-ˈtak-səs How to pronounce phototaxis (audio)
: a movement of a living thing that is made in response to light

Medical Definition

phototaxis

noun
pho·​to·​tax·​is -ˈtak-səs How to pronounce phototaxis (audio)
plural phototaxes -ˌsēz How to pronounce phototaxis (audio)
: a taxis in which light is the directive factor
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