'attackingly' derives from the adjective 'attacking', which comes from the verb 'attack'. 'attack' originates from Old French (later French) 'ataquer'/'attaquer', ultimately influenced by Italian 'attaccare' and a Vulgar Latin formation based on Latin elements meaning 'to fasten or attach'.

'attack' changed from Old French 'ataquer' (and Italian 'attaccare') into Middle English forms such as 'attacken' and eventually became the modern English 'attack'; the present participle 'attacking' developed from the verb and the adverb 'attackingly' was formed by adding the suffix '-ly'.

Initially influenced by a sense of 'to fasten or attach' from the Vulgar Latin formation, the word shifted to mean 'to set upon or assault', and over time its modern sense became 'to take aggressive action'; 'attackingly' now means 'in an aggressive or assaulting manner'.