'faultfinding' originates from English, specifically a compound of 'fault' + 'finding'. 'fault' comes via Old French 'faute' (from Vulgar Latin *fallita, ultimately related to Latin 'fallere' meaning 'to deceive' or 'to fail'), and 'finding' derives from Old English 'findan' meaning 'to discover'.

'faultfinding' developed as the compound 'fault-finding' in modern English (recorded from the 19th century) by combining the noun 'fault' and the present-participle/gerund 'finding', and eventually appears as the noun and adjective 'faultfinding' or 'fault-finding'.

Initially it meant 'the action of finding faults' (a neutral description of discovering faults), but over time it evolved into its common sense of 'a critical tendency to look for and point out faults' (often with negative connotation).