I don't think there is a rule, just that some nouns have identical forms: sheep, species, deer, aircraft are some examples.
Nouns are made plural by adding -s or -es to form the plural, they are called regular plurals; nouns using another form for the plural are called irregular plurals. Some examples of irregular plurals are:child- childrenwoman- womentooth- teethmouse- miceknife- knivesoasis- oasesgoose- geesecactus- cacti
Abstract nouns may not have plurals, as a rule, because there cannot be more than the single concept, such as amazement, honesty, and pessimism. Those that do have plurals are referring to examples of the concept (fears, beliefs, charities) not the concept itself.
parties families
For nouns that end in a consonant + 'y', you need to drop the final 'y' and add '-ies' to form the plural. For example:baby > babiesgallery > galleriescandy > candiesfly > fliesparty > parties
You have to change the y to an I and add the es
Nouns with the 'usual ending' are called regular plurals; plurals formed by adding -s or -es to the end of the word. Examples are: arches birds cats dogs eggs frogs grapes heroes inches jokes knees locks Nouns that form the plural in some other way are called irregular plurals.
Plurals ending in "es" are typically used for nouns that end in s, sh, ch, x, or z sounds, to maintain the correct pronunciation. Plurals ending in just "s" are more common and used for most other nouns.
Nouns that are made plural by adding an 's', 'es', or 'ies' are called regular plurals; nouns that from the plural by another means are called irregular plurals. Some examples of irregular plural common nouns are:singular / pluralman / menwoman / womenchild / childrenperson / peoplemouse / micegoose / geeseox / oxenfoot / feettooth / teethcactus / cactidatum / datamedium / media
Dry is a verb, and only nouns have plurals.
There are only plurals for nouns and empty is a adjective, so there is none.
Yes, nouns ending in y preceded by a vowel form their plurals by adding s. For example, "essay" becomes "essays" and "donkey" becomes "donkeys."
Most common nouns can have plurals, even if the plural is the same as the singular. Other nouns are uncountable, such as the abstract nouns need, greed, or poverty.