Jerusalem

'Ιε?οσολυμα, τα or η, as listed in the BBG lexicon.
Is this saying that the word is feminine when singular and neuter when plural? If so what would the plural of Jerusalem mean?

Ἱε?οσόλυμα is neuter plural but the translation is singular. I am not sure why this city name is plural. Maybe someone know of other examples where a city name is plural.
Why Mounce says that this word is indeclinable I don’t know. It does decline. Matthew 4:25 has the genitive. Luke 23:7 has the dative form.
I assume that the reason he gives both the feminine and the neuter article is because in Matthew 2:3 Ἱε?οσόλυμα is modified by the fem. sg. adjective πᾶσα.
Thayer writes in his lexicon that it is extremely doubtful that this is actually a fem. noun but that; “the unusual coupling of the fem πᾶσα with the neut. plur. Ἱε?οσόλυμα is easily explained by the supposition that the appellative idea ἡ πόλις was in the writer’s mind”

There is a fem. word with the same meaning. It is Ἱε?ουσαλήμ.
This word is indeclinable.

Lots of Greek city names are grammatically plural, e.g., Θῆβαι, Thebes; Ἀθῆναι, Athens. So this isn’t unusual for Greek.

Two forms for this city’s name exist:

Η Ιε?ουσαλήμ -fem. singular, no plural form exists
Τα Ιε?οσόλυμα -neutral, plural, no singular form exists

Jerusalem comes from Η Ιε?ουσαλήμ.

There are suspicions that the first form was the original translation from Hebrew, and the second one was made later according to the name of Athens, which existed only in plural form. The correct name should be Η Ιε?ουσαλήμ.

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Η Ιε?οσόλυμα sounds to me awkward.
Is it mentioned in the bible or gospels and in what time period is it used?

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Jerusalem(Hebrew: Yerushalaim) in Hebrew has an ending like a “dual”.

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