Phototropy

Part of speech: noun

Definitions

1. The tendency of a plant or other organism to grow or turn toward or away from a source of light
2. A biological response in which living things bend, orient, or move in reaction to the direction of illumination
3. Directional growth or movement of a living organism guided by the presence and angle of light

Etymology: Phototropy is a compound built from two Greek elements: "phōto-", the combining form of "phôs" (light), and "-tropy," from "tropē" (turning or turning toward). Together they describe the turning of a living thing toward light, the same idea that the more familiar "phototropism" names. The Greek "phôs" traces back through Proto-Hellenic "pʰáwos" to a Proto-Indo-European root meaning to shine or to appear, so the word's oldest layer is a notion of brightness rather than of plants or biology. The "photo-" element entered English as a combining form, and it now appears in dozens of scientific terms, from "photograph" to "photosynthesis." The word is a modern scientific coinage built from classical parts, not an ancient Greek term, so its meaning was fixed by the scientists who formed it rather than by any ancient usage.

Synonyms: phototropism