1. Singular: Refers to one person, place, thing, or idea (e.g., cat, house, happiness).
2. Plural: Refers to more than one person, place, thing, or idea (e.g., cats, houses, happinesses).
3. Possessive: Shows ownership or possession (e.g., cat's, house's, happiness's).
4. Nominative: Refers to the noun as the subject of a sentence (e.g., The cat sat on the mat).
While these are the basic forms of a noun, some nouns also have other forms such as:
* Gender: Some nouns have distinct forms for different genders (e.g., king/queen, actor/actress).
* Number: While singular and plural cover most nouns, some have special forms for specific quantities (e.g., one/two/many).
It's important to note that the concept of "noun forms" can be a bit broad. The specific forms a noun can take depend on the language and the specific context.