[ trop-ik ]
/ ˈtrɒp ɪk /
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See synonyms for: tropic / tropics on Thesaurus.com

  1. either of two corresponding parallels of latitude on the terrestrial globe, one (tropic of Cancer ) about 23½° N, and the other (tropic of Capricorn ) about 23½° S of the equator, being the boundaries of the Torrid Zone.
  2. the tropics, the regions lying between and near these parallels of latitude; the Torrid Zone and neighboring regions.
Astronomy. either of two circles on the celestial sphere, one lying in the same plane as the tropic of Cancer, the other in the same plane as the tropic of Capricorn.
of, pertaining to, characteristic of, or occurring in the tropics; tropical: romance under the tropic skies of Old Mexico.
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Origin of tropic

1350–1400; Middle English <Latin tropicus<Greek tropikós pertaining to a turn, equivalent to tróp(os) turn + -ikos-ic


non·trop·ic, adjectiveun·trop·ic, adjective

Other definitions for tropic (2 of 2)


a combining form with the meanings “turned toward, with an orientation toward” that specified by the initial element (geotropic), “having an affinity for, affecting” what is specified (lipotropic; neurotropic; psychotropic), “affecting the activity of, maintaining” a specified organ (gonadotropic).
Compare -trophic.

Origin of -tropic

see origin at tropic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does -tropic mean?

The combining formtropic is used like a suffix for a variety of meanings. It can indicate “turned toward, with an orientation toward” something specified by the first part of the word. This sense of -tropic is especially used in biology and botany.

It can also denote “having an affinity for, affecting” a specified thing or “affecting the activity of, maintaining” an organ. Here, it can be synonymous with -trophic, which you can learn more about at our Words That Use article for the form. This sense of -tropic is especially used in biochemistry and physiology.

Closely related to -tropic is -tropous. The combining forms -tropy and -tropism are used to form abstract nouns from concrete nouns using -tropous and -tropic (and vice versa).

Where does -tropic come from?

The form -tropic comes from the Greek suffix –tropos, meaning “pertaining to a turn.” This suffix is based on trópos, “turn,” and tropḗ, “a turning.”

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

Corresponding forms of -tropic combined to the beginning of words are tropo- and trop-. Discover their specific applications of our Words That Use articles for the forms.

Examples of -tropic

One word you may be familiar with that features the form -tropic is hydrotropic, a biological term characterizing plants that orient their growth in the direction of moisture.

The first part of the word, hydro-, from the Greek hýdōr, means “water.” The second part of the word, -tropic, indicates “turned toward.” So, hydrotropic literally translates to “turned towards water.”

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

Break it down!

The combining form thermo- means “heat.” With this in mind, a plant described as thermotropic orients its growth toward what?

How to use tropic in a sentence

British Dictionary definitions for tropic (1 of 2)

/ (ˈtrɒpɪk) /

(sometimes capital) either of the parallel lines of latitude at about 23 1/2 °N (tropic of Cancer) and 23 1/2 °S (tropic of Capricorn) of the equator
the tropics (often capital) that part of the earth's surface between the tropics of Cancer and Capricorn; the Torrid Zone
astronomy either of the two parallel circles on the celestial sphere having the same latitudes and names as the corresponding lines on the earth
a less common word for tropical

Word Origin for tropic

C14: from Late Latin tropicus belonging to a turn, from Greek tropikos, from tropos a turn; from the ancient belief that the sun turned back at the solstices

British Dictionary definitions for tropic (2 of 2)


adj combining form
turning or developing in response to a certain stimulusheliotropic

Word Origin for -tropic

from Greek tropos a turn; see trope
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

Scientific definitions for tropic

[ trŏpĭk ]

Either of the two parallels of latitude representing the points farthest north and south at which the Sun can shine directly overhead. The northern tropic is the Tropic of Cancer and the southern one is the Tropic of Capricorn.
tropics. The region of the Earth lying between these latitudes. The tropics are generally the warmest and most humid region of the Earth. Also called Torrid Zone
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.