1866, echoic of a working steam engine. As a verb, from 1884. Related: Chugged; chugging. Drinking sense attested by 1940s (chug-a-lug), probably imitative of the sound of swallowing.
the engine chugged down the street
chubby
chuck
chuckle
chucklehead
chuff
chug
chukker
chum
chummy
chump
chunder
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