The definition "'case' means (1) a set of circumstances, (2) a lawsuit, (3) a box for holding something" is an example of:

The correct answer is a lexical definition.

A lexical definition refers to the usage of a term or a word to what it is referring to or to where it used for. For example, the word "case", can be used in different languages or terms, it can be used in the court of law, it can also be used in terms of an object that can hold another object.