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