We then say words which are symbols by which a listener is supposed to be able to identify, with more or less fidelity, the relation and the things which we thought of. The relation is technically referred to as a predicate, the things related are called arguments, and the placeholders in the relation that can be occupied by arguments are called cases. You can think of the predicate as a true-false valued function with a particular number of cases. One way to define a predicate is to list every set of arguments that is thus related. Each predicate is represented by a word.
Connected discourse consists of a sequence of clauses, called sentences.
The sentences contain all the other clauses in the speech. A sentence is the symbol set by which the speaker's meaning is presented to the listener. The predicate of the sentence is the relation which the speaker mainly wants the listener to be aware of. Other varieties of sentences are questions and commands. There are also supplementary subordinate clauses which have the same purpose as sentences, but which are buried syntactically.