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