Definition

1. Noun:
   • A unit of speed: A measurement expressing the number of miles traveled in one hour. It is a standard unit for measuring velocity, particularly in countries using the imperial system.
   • A speedometer reading: The numerical value shown on a vehicle's speedometer, indicating the current speed in this unit.

Usage

• As a unit of measurement: Used to quantify how fast something is moving.
  • The speed limit on this highway is 65 miles per hour.
  • The hurricane's winds were sustained at 120 miles per hour.
• As a speedometer reading: Used to describe the specific speed being displayed or traveled.
  • He glanced at the dashboard and saw he was doing 50 miles per hour.
  • The car maintained a steady 70 miles per hour on the interstate.

Advanced Usage

• "Miles per hour" is often abbreviated as mph (always written in lowercase).
  • The new train can reach speeds of 180 mph.
• It is a rate (distance over time). The concept can be applied to other units (e.g., kilometers per hour, feet per second).

Variants and Related Words

• mph: The standard abbreviation for "miles per hour".
• Knot: A unit of speed used in navigation and aviation, equal to one nautical mile per hour. (1 knot is approximately 1.15 mph).
• Kilometers per hour (km/h): The metric unit of speed, where 1 mile per hour is approximately equal to 1.609 kilometers per hour.

Synonyms

• Speed: (General noun) The rate at which someone or something moves.
• Velocity: (Technical noun) The speed of something in a given direction.

Related Phrases

• Revolutions per minute (rpm): A different rate measurement (number of rotations in one minute), often used for engines.
• At a rate of: A phrase used to introduce a speed or other measurement of change.
  • The water flowed at a rate of 5 gallons per minute.

Noun

1. a speedometer reading for the momentary rate of travel
2. the ratio of the distance traveled (in miles) to the time spent traveling (in hours)