tropic /ˈtɹɒpɪk/adjective 4noun 2forms 3 adjective4 •Of, or relating to the tropics; tropical. •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. •Pertaining to, involving, or of the nature of a trope or tropes. •(rare) Hot and humid. noun2 •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, — 1697 •The component of tone or rhetoric in a sentence. formstropics · more tropic · most tropic