'goofy' originates from American English, specifically the word 'goof' + the suffix '-y', where 'goof' meant 'a foolish or silly person' or 'to blunder'.

'goofy' changed from the early 20th century American slang word 'goof' (noun/verb) and eventually produced the adjective 'goofy' and the adverb 'goofily' in modern English.

Initially, it meant 'like a goof; foolish' (derived from 'goof'), and over time it has kept that basic sense while also acquiring a lighter, more playful nuance of 'silly' or 'clownish'.