1》 the rate at which someone or something moves or operates or is able to move or operate.
↘rapidity of movement or action.
2》 each of the possible gear ratios of a bicycle or ( US ) of a motor vehicle.
3》 the light-gathering power or f-number of a camera lens.
↘the duration of a photographic exposure.
↘the sensitivity of photographic film to light.
4》 informal an amphetamine drug, especially methamphetamine.
5》 archaic success; prosperity.
■ verb ( past and past participle sped )
1》 move quickly.
↘( ~ up ) move or work more quickly.
↘ (also ~ something up ) cause to happen more quickly.
2》 (of a motorist) travel at a ~ greater than the legal limit.
3》 informal take or be under the influence of an amphetamine drug.
4》 archaic make prosperous or successful.
at ~ quickly.
up to ~
1》 operating at full ~ or capacity.
2》 informal fully informed or up to date.
OE spēd (n.), spēdan (v.), from the Gmc base of OE spōwan 'prosper, succeed'.