the ratio of the focal length to the diameter of a (camera) lens system
"The photographer checked the camera specs and noted that the new prime lens had an impressive f/1.4 speed, allowing for better performance in low light."
a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression
"The doctor prescribed speed to help her manage her chronic narcolepsy, noting that the medication would keep her alert during long workdays while reducing her hunger."
The state of moving quickly or the capacity for rapid motion.
"The car's speed increased dramatically as it merged onto the highway."
In plain English: Speed is how fast something moves from one place to another.
"The car's top speed is limited by local traffic laws."
move hurridly
"He rushed down the hall to receive his guests"
"The cars raced down the street"
To succeed; to prosper, be lucky.
"The new restaurant is really speeding, as they've already sold out of their special every night since opening."
In plain English: To speed means to go very fast or move quickly.
"The car began to speed up as it approached the highway."
Usage: Use this verb when describing someone who experiences sudden success or good fortune rather than physical velocity. It is often found in phrases like "things are speeding up," meaning circumstances are improving rapidly.
A surname, from nicknames.
"The local baseball team has a player named Speed who earned his last name as a childhood nickname for his quick running style."
The word speed originally meant prosperity or good luck in Old English before its meaning shifted to quickness. It traveled into Middle English with these broader senses of success and fortune before narrowing to its current definition.