1. Introduction
According to a classic definition, “An impersonal verb is a verb that occurs only in third person singular forms, has no specified agent, and has a dummy subject or no subject” (glossary.sil.org/term/impersonal-verb). The notion of ‘impersonal verb’ seems to have been unknown to Arab grammarians, who assumed that all verbs have either a ‘real’ subject (fāʿil) or a ‘substitute for the subject’ (nāʾib fāʿil). Blachère (1975:266) highlights this ambiguity…