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