Nouns ending in -a (often Latin or scientific) add -e to form the plural.
Philadelphia is regular. It follows the -ae Addition rule.
Use plural verbs: "The philadelphiae are ready" (not "is ready").
Yes. The plural philadelphiae is standard across all English variants.
The word philadelphia follows the standard English pluralization rule. When forming the plural, philadelphia becomes philadelphiae. This follows the -ae Addition pattern, which is one of the most common plural rules in English.
Understanding why philadelphia becomes philadelphiae helps with spelling and pronunciation. Nouns ending in -a (often Latin or scientific) add -e to form the plural.
When using philadelphiae in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The philadelphiae are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.