Common nouns are names for people, things, and animals which have regular shapes and boundaries.

Collective nouns are names for people or things which have their members.

Material nouns are names for gas, liquid, and solid which don't have regular shapes and boundaries.

Proper nouns are names for unique people, cities, and countries.

Abstract nouns are names for what we cannot see, smell, taste, hear and feel.

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Hello, thank you for your help.
I have written down the definitions of kinds of nouns in my own way. Do you think my explanations or definitions are plausible?

They read pretty well. There's a bit of awkwardness in the first three, but overall, they're understandable.

Here are what I found when I searched online for definitions:

http://www.englishdaily626.com/grammar.php?014

Life is full of choices, so I must learn to make good ones.

Hello! Thank you for providing your own explanations and definitions for different types of nouns. Overall, your descriptions are quite accurate and capture the essence of each type of noun. However, there are a few points that can be clarified:

1. Common Nouns: Your definition is mostly correct, with the inclusion of "regular shapes and boundaries." While many common nouns may indeed refer to physical objects that have distinct shapes and boundaries, it is not a defining characteristic. Common nouns can also refer to abstract concepts, ideas, or qualities.

2. Collective Nouns: Your definition is accurate, but it is worth noting that collective nouns can refer to groups of people or things, as you mentioned, but they are specifically used to refer to groups as a single unit. Examples include "team," "herd," or "flock."

3. Material Nouns: Your definition is mostly accurate, although it would be more precise to say that material nouns are names for substances rather than just gas, liquid, and solid. Material nouns can include other types of matter, such as plasma or composite materials.

4. Proper Nouns: Your definition is correct, as proper nouns are indeed names for unique individuals (e.g., person's names) or specific places (e.g., cities, countries) that are capitalized.

5. Abstract Nouns: Your definition is accurate, highlighting that abstract nouns represent intangible ideas or concepts. However, it is not necessarily limited to things we cannot sense. Abstract nouns can represent emotions (e.g., love), qualities (e.g., bravery), or concepts (e.g., freedom).

Overall, your explanations are plausible, and with a few minor clarifications, they provide a good understanding of the different types of nouns.