'plainly-shown' originates from the combination of 'plainly' and 'shown', where 'plainly' means 'clearly' and 'shown' is the past participle of 'show'.

'plainly' and 'shown' were combined in modern English to form the adjective 'plainly-shown'.

Initially, it meant 'clearly visible or evident', and this meaning has largely remained the same in modern usage.