Other forms: speeds, speeding
Speed is how fast something moves. At speed, top speed, the speed limit.
In physics speed is distance over time and velocity adds a direction, which is why the two are not interchangeable in a textbook however much they are in speech. Speed of light is the universal limit. Note pick up speed, at full speed, and speed camera; and that speed once meant success or good fortune, which survives in godspeed and in the phrase more haste, less speed — where speed means success rather than quickness.
1nounspeedHow fast something moves.
“The speed limit there is about thirty.”
2verbquicklyTo move or go quickly.
“We watched the boats speeding across the bay in the strong wind.”
Too few real examples of this word to estimate which sense is commonest.
speed is a rate of movement.
Also accepted in games: velocity
Old English sped meant success or prosperity, and the sense of quickness came later. Godspeed and more haste, less speed both preserve the older meaning.
Proto-Indo-European
*speh₁-
Proto-West Germanic
*spōdi — prosperity, success
Old English
spēd — success
Middle English
sped — prosperity, good luck, quickness, success
English, today
speed
From Middle English sped (“prosperity, good luck, quickness, success”), from Old English spēd (“success”), from Proto-West Germanic spōdi (“prosperity, success”), from Proto-West Germanic spōan, from Proto-Germanic spōaną (“to prosper, succeed, be happy”), from Proto-Indo-European speh₁- (“to prosper, turn out well”). Cognate with Scots spede, speid (“success, quickness, speed”), Dutch spoed (“haste; speed”), German Low German Spood (“haste; speed; eagerness; success”), German Sput (“progress, acceleration, haste”). Related also to Old English spōwan (“to be successful, succeed”), Albanian shpejt (“to speed, to hurry”) and Russian спеши́ть (“to hurry”), Latin spēs (“hope, expectation”), spērō (“hope”), perhaps also to Ancient Greek σπεύδω (“to urge on, hasten, press on”).
Etymology from Wiktionary, CC BY-SA