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