Design by Contract is the idea of designing software modules that clearly define what they do through assertions. The only computer language that fully implements Design by Contract is Eiffel (as of July 1999).

"Design by Contract" sometimes happens when one of the lead developers on a project continually mungs up the design with idiotic architectural ideas and useless features. If this goes on too long, the other developers will often try to fix the design by taking up a collection to hire a hit man to get rid of the dumb bastard, or in other words "put out a contract" on him. Hence the term.