نِدَاءٌ
1.
signifies simply The raising the voice; not implying the expression of meaning by speech. (Er-Rághib, TA.)
2.
حَرْفُ نِدَاءِ
A particle of calling, or hailing, or invocation; as يَا.
3.
A vocative particle.
4.
The vocative form of speech.
5.
Also, agreeably with many other instances, like خَلْقٌ in the sense of مَخْلُوقٌ, a verbal noun used in the sense of a pass. particle n., meaning A person or thing called; the object of a vocative particle, synonym with
مُنَادًى.