'steadily-used' is a compound formed from the adverb 'steadily' and the past participle 'used'. 'steadily' derives from the adjective 'steady' plus the adverbial suffix '-ly'. 'steady' ultimately comes from Old English roots meaning 'firm, fixed', while 'used' comes from Old French 'user' from Latin 'uti' meaning 'to use'.

'steadily' developed from Middle English forms of 'steady' (e.g. 'stede', 'stedi') and the addition of the Old English/Old Germanic adverbial/derivational elements; 'used' comes from Latin 'uti' > Vulgar Latin/Old French 'user' > Middle English 'use' with past participle 'used'. These elements combined in Modern English to form the descriptive compound 'steadily-used'.

The basic sense — 'being used in a steady or continuous way' — has remained stable; the compound is a straightforward descriptive phrase rather than a word with a major semantic shift.