watt

Word family

• wattage
  nounB2
• kilowatt
  nounB1
• megawatt
  nounC1
• gigawatt
  nounC1
• watt-hour
  nounC1

Synonym discussion

Sense: noun/1

'Watt' is the basic SI unit of power, so you use it for a precise measurement such as a 60-watt bulb. 'Wattage' means the amount of power something has or uses, rather than the unit name itself, so people talk about a device's wattage. 'Kilowatt' means 1,000 watts and is more common for larger appliances, generators, or household energy use. 'Horsepower' is another unit of power, but it is mainly used for engines and motors. Use 'watt' when you need the exact electrical unit, 'wattage' for general power level, 'kilowatt' for bigger electrical figures, and 'horsepower' for mechanical output.

Common collocations

Etymology

The unit is named after James Watt (1736–1819), a Scottish engineer whose work on steam engines shaped modern power measurement. Scientists later adopted watt as the standard SI unit for electrical power.