'venal' originates from Latin, specifically the word 'venalis', where 'venum' meant 'something for sale.'

'venal' came into English in the late 15th century from Latin 'venalis' (via Medieval/late Latin); the Latin term meant 'for sale' and was used to describe things that could be bought.

Initially it meant 'for sale' or 'able to be bought,' and over time it evolved into the modern sense of 'willing to sell one's integrity; corruptible.'