وَاقٍ
Translation: One who protects.
The active participle identifies the protector. From underlying وَاقِيٌ, the final yāʾ of a defective noun drops in indefinite nominative usage, yielding وَاقٍ.
FormCase/contextSense
وَاقٍindefinite nominativea protector
الْوَاقِيwith definite articlethe protector
The opening wāw remains visible in the participle. Do not impose the imperfect's initial-wāw deletion on every derived noun.