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