'constantly-seen' originates from the combination of 'constant' and 'seen', where 'constant' meant 'occurring continuously over a period of time' and 'seen' is the past participle of 'see'.

'Constantly' evolved from the Latin word 'constans', and 'seen' is derived from the Old English 'seon', eventually forming the modern English term 'constantly-seen'.

Initially, it meant 'frequently observed', and this meaning has largely remained the same in modern usage.