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