Regularities often have exceptions. It is therefore important to have mechanisms both for expressing regularities and their exceptions. Inheritance gives a way of straightforwardly expressing regularities: subtypes of a more general type each have something, some regularity, in common. These subtypes may however differ from their supertype in some way that does not eliminate the usefulness of representing the regularity, and for these cases it is important to incorporate the notion of defaults. Some very well-established examples of the need for such defaults in the lexicon come from morphology: consider a rule for past participle formation which states that -ed is added to the root of the verb. This rule can be applied productively to generate past participle forms of many verbs, including novel verbs. However, there are exceptions. The past participle form of hold, for example, is not holded but held. Other examples can be found in gazdar:87, and some examples of the application of defaults specifically in lexical semantics are discussed in copestake:92. In Section 2.6 I will introduce a representation for nominals which incorporates defaults.