'memory-impairingly' is a Modern English compound formed from 'memory' + 'impair' with the adverbial suffix '-ly'. 'memory' originates from Old English 'gemynd' meaning 'remembrance, thought', and 'impair' comes from Old French (e.g. 'empeirier') ultimately related to Latin roots conveying 'worse'.

'memory-impairingly' developed in Modern English by compounding the noun 'memory' and the verb 'impair' to create the adjective 'memory-impairing', then adding '-ly' to form the adverb 'memory-impairingly'.

The components originally referred to 'remembrance' (memory) and 'to make worse' (impair); combined and adverbialized, they now mean 'in a manner that worsens memory'.