Greek-derived nouns ending in -on change to -a in the plural form.
Common is regular. It follows the Greek -a rule.
Use plural verbs: "The comma are ready" (not "is ready").
Yes. The plural comma is standard across all English variants.
The word common follows the standard English pluralization rule. When forming the plural, common becomes comma. This follows the Greek -a pattern, which is one of the most common plural rules in English.
Understanding why common becomes comma helps with spelling and pronunciation. Greek-derived nouns ending in -on change to -a in the plural form.
When using comma in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The comma are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.