'irregularly-sloped' originates from the combination of 'irregularly' and 'sloped', where 'irregularly' is derived from Latin 'irregularis', meaning 'not regular', and 'sloped' from Old English 'slope', meaning 'incline'.

'irregularly-sloped' changed from the combination of 'irregular' and 'slope' in Middle English, eventually becoming the modern English term 'irregularly-sloped'.

Initially, 'irregularly-sloped' meant 'not having a regular slope', and this meaning has largely remained the same in modern usage.