Choo

Part of speech: interjection, noun

Definitions

1. An onomatopoeic expression mimicking the sound of a steam locomotive or train horn ; a childish or playful interjection often used to imitate a train or to express excitement or anticipation ; a casual sound effect used in storytelling or play to represent the noise made by a moving train or mechanical device
2. A mimicry of the noise produced by a steam engine or train chugging along tracks ; a playful utterance used by children when pretending to be trains or vehicles ; an informal vocalization employed in games or narratives to imitate the rhythmic sounds of machinery in motion
3. A representation of the classic sound associated with old-fashioned trains characterized by a repetitive chugging or blowing noise ; a lighthearted verbal cue used in imaginative play to suggest movement or travel by rail ; a simple sound symbol used to evoke the auditory sensation of mechanical propulsion in casual conversation or performance

Etymology: A steam locomotive's chuffing and hissing gave English speakers a ready-made sound to imitate, and "choo" is that sound written down. It is onomatopoeic, built to echo the puffing of early engines rather than derived from an older word. The doubled "choo-choo" repeats the rhythm of the pistons and wheels, and it became the nursery name for a train almost as soon as children could hear one. Because the word is imitation, it has no single inventor, and the details of its first appearance in print are not something to pin down here. What matters is the pattern: the sound came first, and the spelling followed it. The same process gave English "chug," "puff," and "toot," all words that started as noises a machine or animal made before they became ordinary verbs.

Synonyms: choo-choo, train sound, toot, chug