The English verb 'accelerate' is a product of the Renaissance's hunger for precise scientific vocabulary, borrowed directly from Latin during a period when scholars were systematically raiding classical languages to describe physical phenomena with greater exactness than vernacular English then permitted.
The word derives from Latin 'accelerātus,' the past participle of 'accelerāre,' meaning 'to hasten' or 'to quicken.' This Latin verb was itself a compound: the prefix 'ad-' (meaning 'to' or 'toward,' assimilated to 'ac-' before the consonant 'c') joined with 'celerāre' (to hasten), a verb formed from the adjective 'celer,' meaning 'swift' or 'quick.' The deeper ancestry of 'celer' reaches back to the Proto-Indo-European root *kel-, reconstructed with the meaning 'to drive' or 'to set in motion.'
The PIE root *kel- was remarkably productive across the Indo-European family. In Greek, it produced 'kelēs' (a racehorse) and possibly contributed to 'keleuthos' (a road or path — that which one is driven along). In the Germanic branch, the root's reflexes are debated, but some linguists connect it to Old English 'holian' (to move quickly). The Latin branch
The adjective 'celer' was well established in classical Latin. Cicero used it freely, and it gave its name to one of Rome's earliest social groups: the 'Celeres,' a bodyguard of three hundred horsemen supposedly established by Romulus, the legendary founder of Rome. Their name reflected their primary military virtue — speed. The noun 'celeritas' (swiftness) was a standard term in Roman rhetoric and philosophy, and it survives in English
When 'accelerate' entered English in the 1520s, it initially appeared in scholarly and philosophical texts. The word gained significant traction during the seventeenth century as natural philosophers — Galileo Galilei foremost among them — began developing mathematical descriptions of motion. Galileo's studies of falling bodies and inclined planes required precise terminology for changes in velocity, and 'acceleration' (the noun form, attested from the 1530s) became indispensable. Isaac Newton's Principia Mathematica (1687) cemented
The word's migration from technical to everyday usage followed a pattern common to many scientific terms. By the eighteenth century, writers were using 'accelerate' metaphorically — one could accelerate a process, a plan, or a career. The Industrial Revolution, with its emphasis on speed and efficiency, made the word feel increasingly natural in ordinary conversation. The twentieth century added 'accelerator' in the automotive sense
Across the Romance languages, cognates of 'accelerate' remain transparently related: French 'accélérer,' Spanish and Portuguese 'acelerar,' Italian 'accelerare.' All descend from the same Latin verb and maintain essentially the same meaning, testimony to how thoroughly Latin scientific vocabulary permeated its daughter languages.
The antonym 'decelerate' — formed by substituting the prefix 'de-' (down, away) for 'ac-' — is a surprisingly late coinage, first attested only in 1899. For nearly four centuries, English had 'accelerate' without a precise morphological opposite, relying instead on phrases like 'slow down' or 'reduce speed.' The belated arrival of 'decelerate' underscores how deeply the Latin prefix system remains productive in English word formation, even in the modern era.