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