'ballyhoo' originates from American English, possibly from an earlier variant 'balahoo' or an imitative carnival/shouting cry from the mid-19th century; the exact origin is uncertain.

'ballyhoo' changed from an earlier dialect/variant 'balahoo' used in circus and carnival contexts in the 19th century and eventually became the modern English word 'ballyhoo' with its current spelling and usage.

Initially, it referred to a loud cry or shout used to attract attention (or the shout itself), but over time it evolved into the current sense of 'sensational publicity' or exaggerated promotion.