Watt

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late 19th century: named after James Watt (see Watt, James).

wiktionary

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Named after Scottish engineer James Watt. For the surname, see Watt.

etymonline

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watt (n.)

unit of electrical power, 1882, in honor of James Watt (1736-1819), Scottish engineer and inventor. The surname is from an old pet form of Walter and also is in Watson.