tropic

Etymology

From Late Latin tropicus (“of or pertaining to the solstice, as a noun, one of the tropics”), from Ancient Greek τροπικός (tropikós, “of or pertaining to a turn or change; or the solstice; or a trope or figure; tropic; tropical; etc.”), from τροπή (tropḗ, “turn; solstice; trope”).

noun

1. Either of the two parallels of latitude 23°27′ north and south of the equator; the farthest points at which the sun can be directly overhead; the boundaries of the torrid zone or tropics.
   O conſider my caſe, moſt blisfull Queen, […] Diſpell thoſe Clouds which hover 'twixt my King and his higheſt Counſell, […] that my great Law-making Court be forced to turn no more to polemicall Committees, […] but that they may come again to the old Parliamentary Rode, To the path of their Predeceſſours, to conſult of means how to ſweep away thoſe Cobwebs that hang in the Courts of Juſtice, and to make the Laws run in their right Channell; to retrench exceſſive fees, and finde remedies for the future, that the poor Client be not ſo peeled by his Lawyer, and made to ſuffer by ſuch monſtrous delays, that one may go from one Tropick to the other, and croſſe the Equinoctiall twenty times, before his ſute be done; […] 1645, James Howell, “England’s Tears, for the Present Wars, which for the Nature of the Quarrel, the Quality of the Strength, the Diversity of Battels, Skirmishes, Encounters, and Sieges, (Happened in so Short a Compasse of Time) Cannot be Parallel’d in Any Precedent Age”, in ΔΕΝΔΡΟΛΟΓΊΑ [DENDROLOGIA]: Dodona’s Grove, or The Vocall Forrest. The Third Edition More Exact and Perfect than the Former; with the Addition of Two Other Tracts: viz. Englands Tears for the Present Wars. And The Pre-eminence of Parlements, 3rd edition, Cambridge: Printed by R. D. for Humphrey Moseley, and are to be sold at his shop at the Prince's Arms in S. Pauls Church-yard, →OCLC, page 189
   For since on ev'ry Sea, on ev'ry Coast, Your Men have been distress'd, your Navy tost, Sev'n times the Sun has either Tropick view'd, 1697, John Dryden, The Works of Virgil, Aeneas, Book I, lines 1062-64

adj

1. Of, or relating to the tropics; tropical.
2. (weather, climate) Hot and humid.
3. (biochemistry, incomparable) Having the quality of indirectly inducing a biological or chemical change in a system or substrate.
   The binding of oxygen to hemoglobin is allosterically regulated by various tropic factors, such as BPG and acidity.
4. Pertaining to, involving, or of the nature of a trope or tropes.
   This process of tropic change, once identified in nostalgia poems, can be applied to a range of new and emerging genres in various periods. Identifying the tropes of nostalgia, in other words, allows us to appreciate the process[…] 2006, Aaron Santesso, A Careful Longing: The Poetics and Problems of Nostalgia, University of Delaware Press, page 12
   Tropes may also interact with other tropes: a trope (for example, a metonymic association) may become an element in a different trope (for instance, a metaphor), and thus undergo a transformation of its tropic identity. 2006-10-27, Jens Kreinath, J.A.M. Snoek, Michael Stausberg, Theorizing Rituals, Volume 1: Issues, Topics, Approaches, Concepts, BRILL, page 702
   As these examples indicate, the functioning of ritual symbols as “pivots” for the projection of efficacy between frames involves the use of symbols as tropes. The tropic uses of symbols in ritual specify the aspects of their range of[…] 2021-01-14, Marko Živković, Jamin Pelkey, James W. Fernandez, Tropological Thought and Action: Essays on the Poetics of Imagination, Berghahn Books, page 300