زَيْدٌ قَائِمٌ — “Zayd is standing.”
Here زَيْدٌ is nominative but is not a fāʿil; it is the mubtadaʾ, and قَائِمٌ is the predicate. In قَامَ زَيْدٌ, Zayd is the fāʿil. Thus nominative is a case, whereas fāʿil is a syntactic role; the terms are not interchangeable.
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Al-Marfūʿāt: The Fāʿil, Its Definition and Full Parsing
زَيْدٌ قَائِمٌ — “Zayd is standing.”
Here زَيْدٌ is nominative but is not a fāʿil; it is the mubtadaʾ, and قَائِمٌ is the predicate. In قَامَ زَيْدٌ, Zayd is the fāʿil. Thus nominative is a case, whereas fāʿil is a syntactic role; the terms are not interchangeable.