What is the correct plural form for the word dictionary?

All these dictionaries give plurals for English nouns that have irregular plurals. For example, Merriam-Webster here says "plural mediums or me. · dia". If one of thesedictionaries does not explicitly give a plural for a noun, the noun has a regular plural, meaning you add an "s" or an "es".  hope this works ;)

Idon’t know who knows i do know who does not know me