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