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tropism

[ troh-piz-uhm ]
/ ˈtroʊ pɪz əm /
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noun Biology.
an orientation of an organism to an external stimulus, as light, especially by growth rather than by movement.
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Origin of tropism

First recorded in 1895–1900; independent use of -tropism

OTHER WORDS FROM tropism

tro·pis·mat·ic [troh-piz-mat-ik], /ˌtroʊ pɪzˈmæt ɪk/, adjectivetro·pis·tic [troh-pis-tik], /troʊˈpɪs tɪk/, adjective

Other definitions for tropism (2 of 2)

-tropism

variant of -tropy.

Origin of -tropism

see origin at -tropy, -ism
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

WORDS THAT USE -TROPISM

What does -tropism mean?

The combining formtropism is used like a suffix to form abstract nouns corresponding to adjectives ending in -tropic and -tropous, such as how neurotropism is the quality of being neurotropic.

These endings variously denote “turning, changing, reacting, responding.” Learn more about -tropic and -tropous at our Words That Use articles for the forms.

Where does -tropism come from?

The form -tropism comes from the Greek trópos, “turn,” and tropḗ, “a turning,” combined with -ism, a prolific suffix also derived from Greek that commonly indicates “action, practice, state, condition.”

The biology term tropism, “an orientation of an organism to an external stimulus, as light, especially by growth rather than by movement,” is an independent use of the combining form –tropism.

The Greek trópos is also the source of the words trope and tropical. It’s your turn to make the connection between “turning,”  figures of speech, and the tropics at our entries for the words.

The combining form -tropism is a variant of –tropy, as in allotropy. Want to know more? Read our Words That Use –tropy article.

Corresponding forms of -tropism combined to the beginning of words are tropo- and trop-, which you can also learn more about at our Words That Use articles for the forms.

Examples of -tropism

One example of a biological term that features –tropism is chemotropism, meaning “oriented growth or movement, especially of a plant, in response to a chemical stimulus.”

The first portion of the word, chemo-, means “chemical.” The second portion of the word, –tropism, indicates “turned toward.” Chemotropism literally translates to “turned towards a chemical.”

What are some words that use the combining form -tropism?

What are some other forms that -tropism may be commonly confused with?

Break it down!

The combining form helio- means “sun.” Heliotropism can refer to plants whose flowers do what?

Hint: sunflowers are known for this quality!

How to use tropism in a sentence

British Dictionary definitions for tropism (1 of 2)

tropism
/ (ˈtrəʊpɪzəm) /

noun
the response of an organism, esp a plant, to an external stimulus by growth in a direction determined by the stimulus

Derived forms of tropism

tropismatic, adjectivetropistic (trəʊˈpɪstɪk), adjective

Word Origin for tropism

from Greek tropos a turn

British Dictionary definitions for tropism (2 of 2)

-tropism

-tropy


n combining form
indicating a tendency to turn or develop in response to a certain stimulusphototropism

Word Origin for -tropism

from Greek tropos a turn
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

Medical definitions for tropism (1 of 2)

tropism
[ trōpĭz′əm ]

n.
The turning or bending movement of a living organism or part toward or away from an external stimulus, such as light, heat, or gravity.

Other words from tropism

tropic, tro•pistic adj.

Medical definitions for tropism (2 of 2)

-tropism

suff.
Tropism:stereotropism.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for tropism

tropism
[ trōpĭz′əm ]

The growth or movement of a living organism or anatomical structure toward or away from an external stimulus, such as light, heat, or gravity. See also geotropism hydrotropism phototropism.

Other words from tropism

tropistic adjective
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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