noun

1. the act or state of moving rapidly; swiftness; quick motion
2. 1. the rate of movement or motion; velocity (sense )
   2. the magnitude of a velocity (sense )
   3. the rate or rapidity of any action reading speed
3. a gear or arrangement of gears for the drive of an engine or bicycle a truck with five forward speeds
4. Informal one's kind or level of taste, capability, etc.
5. ☆ Slang any of various amphetamine compounds, esp. methedrine
6. Archaic luck; success; prosperity to wish someone good speed
7. Photog.
   1. the sensitivity of film to light, expressed in various numerical scales
   2. the widest effective aperture of a camera lens
   3. the length of time the shutter is opened for an exposure

Etymology: ME sped < OE spæd, wealth, power, success, akin to spowan, to prosper, succeed < IE base *spēi-, to flourish, expand > space, spare

adjective

intransitive verb sped or speeded speed′ed, speeding speed′·ing

1. to move rapidly, esp. more rapidly than is safe or allowed by law
2. Archaic
   1. to get along; fare
   2. to have fortune, good or bad
   3. to have good fortune; prosper; succeed

transitive verb

1. to help (a project) to succeed; aid; promote
2. to wish Godspeed to to speed the parting guest
3. to send, convey, or cause to move, go, etc. swiftly to speed a letter on its way
4. to cause or design (a machine, etc.) to operate at a certain speed or speeds
5. Archaic to cause to succeed or prosper