Dictionary.com
definitions

phototaxis

or pho·to·tax·y

[foh-tuh-tak-sis]

noun Biology.

movement of an organism toward or away from a source of light.

Origin of phototaxis

First recorded in 1900–05; photo- + -taxis
Related formspho·to·tac·tic [foh-tuh-tak-tik] /ˌfoʊ təˈtæk tɪk/, adjectivepho·to·tac·ti·cal·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for phototaxis

phototaxis

phototaxy

noun

the movement of an entire organism in response to light
Derived Formsphototactic (ˌfəʊtəʊˈtæktɪk), adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
phototaxis in Medicine

phototaxis

[fō′tō-tăk′sĭs]

n.

The movement of an organism or cell toward or away from a source of light.
Related formspho′to•tac′tic (-tăk′tĭk) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.