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