اللَّهُ أَحَدٌ
Allah is uniquely One. (112:1)
Aḥad is indefinite and nominative. In this predication it affirms unique oneness without partner, not merely the first number in a countable series. Treating the word only as a numeral would miss the force of the theological proposition.
Its indefiniteness must be understood alongside its lexical meaning and the surah’s larger argument. There is no universal rule that every indefinite noun communicates uniqueness; rhetorical meaning depends on context.