or pho·to·tax·y

[ foh-tuh-tak-sis ]
/ ˌfoʊ təˈtæk sɪs /

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 forms

pho·to·tac·tic [foh-tuh-tak-tik] /ˌfoʊ təˈtæk tɪk/, adjectivepho·to·tac·ti·cal·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for phototaxis



/ (ˌfəʊtəʊˈtæksɪs) /


the movement of an entire organism in response to light

Derived Forms

phototactic (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

Medicine definitions for phototaxis


[ fō′tō-tăksĭs ]


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

Related forms

pho′to•tactic (-tăktĭk) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.