A non-terminal element operates in context-free grammar. This form of grammar is necessary to enable the translation of source code to object code in a meaningful way, so as to preserve all the information. Specifically, a non-terminal element, which can also be called a variable, is capable of being broken down into other elements, called tokens or terminal elements. A terminal element cannot be broken down into other symbols. Terminal elements of source code are typically passed on to the parser, which is a program that dissects the source code in order that the code can be translated into object code.

A second meaning for non-terminal relates to query languages such as the Abundantia Verborum, languages that are hierarchical, or tree-like, in their structure. The hierarchical approach to problem solving in this scheme is also referred to as a semantic tree. In this structure, the non-terminal nodes types the AND, OR, and NOT function to combine so-called atomic queries--that address a single issue and are not qualifiable--into more complex queries. The non-terminal node types are Boolean operators; that is, they produce an outcome that is true or false. The larger queries, which are qualifiable due to the AND, OR, and NOT nodes, enable a more all-encompassing query to be constructed.