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