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