tropic

noun

1. Either of the two parallels of latitude 23°26′ 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.

   “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,”

2. The component of tone or rhetoric in a sentence.
3. (alt-of, alternative)Alternative form of tropic (one of two specific lines of latitude that divide the Northern and Southern hemispheres, respectively; the Tropic of Cancer and the Tropic of Capricorn).

adj

1. Of, or relating to the tropics; tropical.
2. (rare)Of, or relating to the tropics; tropical.
3. (not-comparable)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[…]”

   “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.”

   “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[…]”