; Pattern
: Syntax describing expected structure in the scrutinee, plus specification of portions of the scrutinee to extract (bindings) or ignore (wildcards). Pattern languages can be rich; see below for terminology denoting specific kinds of pattern.

; Scrutinee
: The value to be examined and matched against a pattern. In most cases, this will be a data structure of some kind, with type dual to the pattern being applied. Also known as the subject value or discriminant.