'proficiently-used' originates from English by combining 'proficiently' (from 'proficient') and 'used' (past participle of 'use'). 'Proficient' ultimately derives from Latin 'proficere,' where 'pro-' meant 'forward' and 'facere' (from which the '-fic-' element comes) meant 'to make/do.' 'Use' comes from Latin 'uti,' later appearing in Old French as 'user.'

'Proficient' changed from Latin 'proficere' (to make progress) through Medieval Latin/Old French forms into Middle English 'proficient' and then modern English 'proficient.' 'Use' changed from Latin 'uti' to Old French 'user' and Middle English 'usen,' eventually becoming modern English 'use.' The compound 'proficiently-used' is a modern English formation combining the adverbial form of 'proficient' with the past participle 'used.'

Initially, the root for 'proficient' carried the sense of 'making progress' or 'beneficial'; over time it shifted to mean 'skilled' or 'competent.' 'Use' originally meant 'to employ' or 'to make use of' and has retained that sense. Together the compound evolved to mean 'employed in a skilled or effective way.'