'preparedly' originates from English word-formation: the adjective 'prepared' + the adverbial suffix '-ly'. 'Prepared' ultimately comes from Latin 'preparare', where 'prae-' meant 'before' and 'parare' meant 'to make ready'.

'preparedly' was formed in Modern English from the past-participle/adjective 'prepared' (from Middle English 'preparen'/'prepard') + the suffix '-ly', which creates adverbs in English; 'preparare' > Old French/Medieval Latin forms influenced Middle English 'prepare'/'prepared'.

Initially related to the verb sense 'to make ready' (to prepare); over time the derived adjective 'prepared' came to mean 'made ready', and the adverbial form 'preparedly' came to mean 'in a made-ready manner' or 'with prior preparation'.