Concept: argument (expression)

Definition

An argument (expression) is a nominal or a person index that occupies an argument slot.

Croft's comparative concept
argument phrase:

argument phrase (CXN) = a referring phrase that refers to an argument. Example: in The tree fell, the tree is an argument phrase because it is a referring phrase that refers to the argument of the predicate – namely, the tree that fell. Argument phrases are divided into core argument phrases (subject phrase, object phrase) and oblique argument phrases. (Sections 2.2.2, 6.6.1) ❡

argument (INF ) = a referent of which something is being predicated. Example: in Masha is nice, being nice is being predicated of the referent Masha, and hence the referent Masha is an argument. Most referents are also arguments, but it is possible for a ref- erent to “stand alone” in discourse, particularly in spoken discourse, independent of any predication. Arguments are divided into core arguments (subject and object) and peripheral arguments. (Sections 2.1, 6.1.1)

Wikipedia
argument