'venereal' originates from Latin, specifically from the adjective 'Venerēus' (or 'veneralis') derived from 'Venus', where 'Venus' referred to the Roman goddess of love and therefore meant 'pertaining to sexual love or desire'.

'venereal' entered English via Late Latin/Medieval Latin forms (for example 'veneralis'/'venereus') and was adopted into Middle/Modern English as 'venereal' by the 17th century, with senses tied to Venus (sexual love) and later specialized to denote diseases associated with sexual contact.

Initially, it meant 'of or relating to Venus / sexual love'; over time the sense specialized to 'relating to sexually transmitted disease' (i.e., diseases transmitted by sexual contact).