'madcap' originates from English, formed from the words 'mad' and 'cap', where 'mad' meant 'insane' or 'frenzied' and 'cap' (in older slang) referred to 'head' or a 'foolish person'.

'madcap' appeared in early 17th century English as a compound describing a 'rash or impetuous person' and has remained in use with similar senses into modern English.

Initially it meant 'a reckless or foolish person'; over time it also became widely used as an adjective meaning 'recklessly impulsive' or 'wildly foolish'.