[…] in ['there was a riot, in the village, yesterday'] 'there was' marks 'the riot' as the predicate i.e. as the element around which others gravitate and in relation to which their function will be marked […]
- Martinet (1962), Pag. 44

Traditionally, the term ‘predicate’ is defined in reference to the subject-predicate complex and would seem to designate everything in the clause that is not the subject, or some dependent of the subject. Beside, ‘predicate’ implies some assertion, so that a question or an order would not contain any predicate. If the term is to be retained by contemporary linguistcs, we shall want to use it in reference to monotematic segments which, by themselves, may constitute a complete, out-of-situation utterance, and also to the same segments when accompanied by various expansions (complements), but independently of them. Within the subject-predicate complex, ‘predicate’ should, in similar fashion, apply to any segment that is, jointly with the subject, constitutive of the minimal utterances, thus including from it its various complements.
- Martinet (1962), Pag. 62