'inadequacy' originates from Latin, specifically the word 'inaequatus,' where 'in-' meant 'not' and 'aequatus' meant 'equal or level.'

'inaequatus' transformed into the French word 'inadequat,' and eventually became the modern English word 'inadequacy' through Middle English.

Initially, it meant 'not equal or level,' but over time it evolved into its current meaning of 'insufficient or lacking.'