Rapidity

Part of speech: noun

Pronunciation: /ɹəˈpɪdɪti/

Definitions

1. The quality of moving, acting, or happening very quickly without delay
2. A state characterized by swift speed or promptness in action or change
3. The attribute of occurring or being performed at a high rate of speed

Etymology: "Rapidity" is a straightforward formation: it joins "rapid" with the suffix "-ity", which turns an adjective into a noun for a quality. The adjective "rapid" comes from Latin "rapidus", meaning seizing or carrying off, from "rapere", to snatch or seize. That original sense of forcible swiftness, something snatched along quickly, is still visible in the modern meaning of speed. The noun itself was borrowed from French "rapidité", which in turn came from Latin "rapiditas". English took it on as a ready-made abstract noun, so the word describes the quality of swiftness rather than any particular fast movement. Its history is therefore mostly the history of its two halves: a Latin verb of seizing, and a suffix that made it possible to talk about speed as a thing in itself.

Synonyms: speed, swiftness, quickness, celerity, velocity

Antonyms: slowness, delayed, lethargy, tardiness, inactivity