'giddily' originates from Old English, specifically the word 'gidig', where 'gidig' meant 'mad, frantic'; the modern adverb is formed by adding the adjective-forming change (giddy) plus the suffix '-ly'.

'giddily' changed from Middle English forms such as 'gidi' / 'gidy' (adjective) and later 'giddy', and eventually became the modern English adverb 'giddily' through the addition of the suffix '-ly'.

Initially, it meant 'mad, frantic' (Old English sense), but over time it evolved into meanings like 'dizzy, lightheaded' and figuratively 'frivolous' or 'excessive'.