The words in this list all mean an undertaking to make the meaning of something clear to oneself or to someone else. Explanation is the broadest of these words, and is applied to ideas, utterances, actions or operations. It is often used in place of may of the other words in the list.

A definition is, etymologically, a setting of limits or boundaries. In this context it is used to give the exact meaning of a word or phrase, or to delimit a problem or an undertaking. In a debate, one is often required to give a definition (or explanation ) of technical terms to be used.

A description is a detailed account of the important aspects of something. A description may have as its object merely the pleasure of the listener or reader: a description of a sunset. As here considered, however, a description has a didactic purpose. Thus, to give a description of the parts of an intricate machine is to give an explanation of how it works.

An exposition is a long, detailed, often scholarly setting forth of all the salient points of an argument, proposal, theory or the like: a theoretical physicist who published an exposition of his ideas in a scientific monograph. Annotation and commentary are expositions in the fields of law and theology, respectively, although both are also used in more general contexts as well. Annotation can applies to a series or body of notes or remarks.

Interpretation , in this context, is the application of imagination or insight to the explanation of a difficult passage in literature, a baffling problem, an action difficult to account for, a dream, or the like: a grave interpretation of the curt diplomatic message; a disputed interpretation of an obscure passage from Eliot’s The Wasteland .