2. A reference to something taking place within a short time or quickly: With the heavy rainfall, the rapid growth of the forest was predictable.
3. Descriptive of moving or acting with great speed: Because of her rapid skills in sorting the tray of polished stones, the new worker, Janet, earned a bonus in her pay.
4. Characterized by speed: The rapid gesture of the swordsman distracted his opponent during the competition and that’s how Tom won the contest.
5. Etymology: rapid is traced back to 1634, from Latin rapidus, "hasty, snatching", from rapere, "hurry away, carry off, seize, plunder" (related to Greek ereptomai, "devour"; harpazein "snatch away").
Rapids is from 1765, from French rapides, applied by French voyagers to North American rivers.
Like "rape" and "rapture", rapid came ultimately from Latin rapere, "seize by force". From this was derived the adjective rapidus, which originally indicated "carrying off by force".
The notion of "swiftness" soon became incorporated into the meaning and although the Latin adjective retained its original connotations of "violence" (it suggested "impetuous speed" or "haste); by the time it reached English, it had simply become synonymous with "quick" or "fast".
2. The rapid involuntary movement of the eyes that occurs when an image of interest falls on the retina at a distance from the fovea (small depression), as normally occurs when reading the printed page.
3. The series of small, jerky movements of the eyes when changing focus from one point to another.
4. The abrupt rapid small movements of both eyes; such as, when the eyes scan a line of print.
The saccades can be divided into two distinct groups: the major saccades which are easily observed with the naked eye and the minor saccades that are virtually unobservable without special instrumentation.
The word saccade is borrowed from French. It is derived from Old French sachier, "to shake". In horse riding, a saccade is the brusque shaking given to the reins of a horse which is used as a signal to the horse by the rider.