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