cad

Etymology

Short for caddie, from Scots, from French cadet, from dialectal capdet (“chief, captain”), from Latin capitellum, diminutive of caput (“head”).

noun

1. A low-bred, presuming person; a mean, vulgar fellow, especially one that cannot be trusted with a lady.
   The most rapid and most seductive transition in all human nature is that which attends the palliation of a ravenous appetite.[…]Can those harmless but refined fellow-diners be the selfish cads whose gluttony and personal appearance so raised your contemptuous wrath on your arrival? 1922, Ben Travers, chapter 5, in A Cuckoo in the Nest
2. (archaic) A person who stands at the door of an omnibus to open and shut it, and to receive fares; a bus conductor.
   We will back the machine in which we make our daily peregrination from the top of Oxford-street to the city, against any buss on the road, whether it be for the gaudiness of its exterior, the perfect simplicity of its interior, or the native coolness of its cad. c. 1835, Charles Dickens, "Omnibuses" (in Sketches by Boz)
3. (UK, obsolete, slang) An idle hanger-on about innyards.