'unevenly-declined' originates from the combination of 'unevenly' and 'declined', where 'unevenly' means 'not level or smooth' and 'declined' means 'sloped or angled downward'.

The term 'unevenly-declined' combines the adverb 'unevenly' with the past participle 'declined', forming a compound adjective.

Initially, 'unevenly' meant 'not even' and 'declined' meant 'sloped downward', and this meaning has largely remained the same in modern usage.