Real Dictionary

cad
countable noun: If you say that a man is a cad, you mean that he treats other people, especially women, badly or unfairly.
uncountable noun: CAD refers to the use of computer software in the design of things such as cars, buildings, and machines. CAD is an abbreviation for 'computer aided design'.

CAD in American English
a man or boy whose behavior is not gentlemanly
acronym: computer-aided design
noun: an ill-bred man, esp. one who behaves in a dishonorable or irresponsible way toward women

cad in British English
noun: someone who does not treat other people with courtesy and consideration
noun acronym for: computer-aided design

CAD in Electrical Engineering
abbreviation: CAD is the use of computer software in the design of electrical systems.