What word does your mother always say?
(OOD) A design method in which a system is modelled as a collection of cooperating objects and individual objects are treated as instances of a class within a class hierarchy. Four stages can be identified: identify the classes and objects, identify their semantics, identify their relationships and specify class and object interfaces and implementation. Object-oriented design is one of the stages of object-oriented programming.
["Object-oriented analysis and design with applications", Grady Booch, 2nd ed., pub. Benjamin/Cummings, Redwood CA, 1994].