heliotropism

noun

he·​li·​ot·​ro·​pism ˌhē-lē-ˈä-trə-ˌpi-zəm How to pronounce heliotropism (audio)
: phototropism in which sunlight is the orienting stimulus
heliotropic
ˌhē-lē-ə-ˈtrō-pik How to pronounce heliotropism (audio) -ˈträ- How to pronounce heliotropism (audio)
adjective

Word History

Etymology

borrowed from French héliotropisme, from hélio- helio- + -tropisme -tropism, after héliotrope heliotrope

Note: The term was probably introduced by the Swiss naturalist Jean Senebier (1742-1809) in Physiologie végétale, tome 3 (Geneva, 1800?), p. 182.

First Known Use

circa 1854, in the meaning defined above

Time Traveler
The first known use of heliotropism was circa 1854

Rhymes for heliotropism

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Browse Nearby Words

heliotropin
heliotropism
Heliotropium
See all Nearby Words

Cite this Entry

“Heliotropism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heliotropism. Accessed 4 Feb. 2026.

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Kids Definition

heliotropism

noun
he·​li·​ot·​ro·​pism ˌhē-lē-ˈä-trə-ˌpiz-əm How to pronounce heliotropism (audio)
: a turning or curving (as of a sunflower head) toward the sunlight

Medical Definition

heliotropism

noun
he·​li·​ot·​ro·​pism ˌhē-lē-ˈä-trə-ˌpiz-əm How to pronounce heliotropism (audio)
: phototropism in which sunlight is the orienting stimulus
heliotropic
-lē-ə-ˈtrōp-ik How to pronounce heliotropism (audio) -ˈträp- How to pronounce heliotropism (audio)
adjective
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