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