rapidity

English

Etymology

From rapid +‎ -ity, from French rapidité, from Latin rapiditas.

Pronunciation

• IPA^(key): /ɹəˈpɪdɪti/

• Audio (Southern England):

  (file)

Noun

rapidity (countable and uncountable, plural rapidities)

1. speed, swiftness; the condition of being rapid
   • 1944 November and December, Talisman, “A Broadening Horizon”, in Railway Magazine, page 340:

     Although appreciating the rapidity and frequency of the Southern electric services I was now to use on short journeys, I became more than ever convinced that electric traction offers very little of interest to the dyed-in-the-wool railwayist.

2. (physics) A measure of velocity relative to the speed of light; defined as artanh(v), where artanh is the hyperbolic arctangent, and v = speed (with c = speed of light = 1).
3. (physics) A measure of the velocity of a particle in a beam relative to the beam's axis

Derived terms

• midrapidity
• pseudorapidity

Translations

speed, swiftness

• Bulgarian: бързина (bg) f (bǎrzina)
• Esperanto: rapideco
• French: rapidité (fr) f, célérité (fr) f
• Greek: ταχύτητα (el) f (tachýtita)
• Ido: rapideso (io)
• Italian: rapidità (it) f
• Polish: szybkość (pl) f
• Romanian: rapiditate (ro) f
• Russian: быстрота́ (ru) f (bystrotá), ско́рость (ru) f (skórostʹ)
• Spanish: rapidez (es) f, celeridad (es) f
• Swedish: fart (sv) c, snabbhet (sv) c, snärt (sv) c
• Tagalog: bilis, tulin (tl)
• Volapük: vif (vo)