Watt

How to spell watt

4 letters · 1 syllable

How to pronounce watt

What does watt mean?

1. nounThe SI unit of power, equal to one joule per second, used to measure how much energy a device uses or produces.

Watt in a sentence

• The old bulb drew one watt of electrical power in standby mode.

• One watt is defined as a single joule of energy per second.

Where does watt come from?

Language of origin: Other

This word is an eponym, meaning it was coined from a person's name rather than from an older root. It honours James Watt, the Scottish engineer (1736 to 1819) whose improvements to the steam engine helped power the Industrial Revolution. The British Association for the Advancement of Science formally adopted the watt as the standard unit of power in 1882, decades after Watt's death, and it became part of the international metric system. The surname Watt itself is a medieval pet form of the name Walter, which came into English through the Normans and traces back to Germanic roots meaning 'ruler of the army'. Because the unit is named after a man, it keeps the double 't' of his surname, which is the detail that distinguishes it in writing from the ordinary question word 'what'.

How the word is built

• watt (eponym from the surname Watt)
• no affixes; it is a proper-name-derived unit, written lowercase as the unit but capitalised as the symbol W