What are the subtopics under noun?

Answer 1

I'm not sure what you're after, exactly, but nouns can have the following qualities:

• nouns can be subjects or objects. This is most obvious with pronouns, which change depending on whether they are used as subject or object (he vs. him...)
• Nouns (particularly Germanic nouns) can have case, meaning that their form changes depending on how they are used. for example: 'he is strong' vs. 'he has strength'; strong and strength are two cases of the word strong.
• in some cases verbs can act as nouns, usually by adding 'ing' as a suffix (called a gerund). e.g., the verb 'fight' is often used in noun form as 'fighting'.

Answer 2

Sub-groups of Nouns:

Singular nouns are words for one person, place, or thing.

Plural nouns are words for more than one person, place, or thing.

Common nouns are nouns are general words for any person, place, or thing, such as bookkeeper, tent, unicycle, crossroads, month, antelope, city, and innocence. Common nouns are capitalized only when they are the first word of a sentence.

Proper nouns are the names or titles of specific people, places, things, or titles; such as General Eisenhower, the Tower of London, New Year's Day, the Great Depression, the Battle of Gettysburg, or 'War and Peace' by Leo Tolstoy. Proper nouns are always capitalized.

Abstract nouns are words for things that you cannot detect with your physical senses; you cannot see, hear, smell, taste, or feel them. An abstract noun is a certain category of things that are known, learned, understood, or felt emotionally. Abstract nouns include tolerance, optimism, hatred, leisure, trust, and gratitude.

Concrete nouns are words for things with which you can physically interact, things that can be experienced by any of the five physical senses; things that can be seen, heard, smelled, tasted, or touched. Concrete nouns include person, goat, ferry, sunflower, blueberry, game, blouse, knife, snow, and Clarinet.

Count nouns are nouns for things that can be counted, that have a singular and plural form, for example one hand, two hands; one monkey, a barrel of monkeys; one dollar, five dollars, or a million dollars.

Non-count (mass) nouns are things that can't be counted; they are words for substances such as sand, rice, aluminum, oxygen; and some of the abstract nouns such as knowledge, harm, advice, news, or homework. Multiples of non-count substance nouns are expressed as tons of sand and grains of sand, or a sack of rice and a cup of rice. The plural forms of non-count nouns are reserved for 'types of' or 'kinds of', such as two types of rices are brown and white.

Partitive nouns (also called a noun counter) are nouns used to count or quantify an uncountable noun.
Examples of partitive nouns are a cup of coffee, a quart of milk and a loaf of bread.

Possessive nouns are words that show that something in the sentence belongs to that noun; possessives are shown by adding an apostrophe -s to the end of the word, or occasionally just an apostrophe for some nouns that already end with -s.

Examples of possessive nouns are the child's toys, the teacher's desk, the elephant's baby, the bus'stire, or the bosses' meeting.

Collective nouns are words used to group nouns for people or things. Some examples are a crowd of onlookers, a bouquet of flowers, a herd of cattle, a team of players, a row of houses, or a pod of whales.

Compound nouns are nouns made up of two or more words merged into one word with a meaning of its own. There are three types of compound nouns:

• open spaced: tennis shoe, front door, paint brush
• hyphenated: mother-in-law, fifty-five, six-pack
• closed: bathtub, Baseball, houseboat

Gerunds (verbal nouns) are the present participle of a verb (the -ing word) that functions as a noun in a sentence; for example:

• 'Walking is good exercise.'
  

Material nouns are words for things that other things are made from. Some examples are flour, milk, concrete, sand, oil, plastic, cotton, fabric, wool, or wood.

Attributive nouns (also called a noun adjunct) are nouns that modify another noun and function as an adjective; for example almond cookies; computer keyboard; or ranch dressing on a house salad.