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