The correct plural of “octopus” is “octopuses.”
People often write “octopi” instead because they assume that the plural noun is formed in the same way as Latin loanwords such as “fungus/fungi.” But “octopus” actually comes from Greek, where its original plural is “octopodes.” In English, it instead has the regular plural form “octopuses.”
For example, you might write “There are four octopuses in the aquarium.”
A possessive noun is a noun like “farmer’s” that is used to indicate ownership (possession). It normally comes before another noun that indicates the thing possessed (e.g., “the farmer’s pitchfork”).
Possessive nouns are formed from regular nouns by adding an apostrophe followed by an “s,” or, in the case of plural nouns that already end in “s,” by just adding an apostrophe.
Possessive is an adjective meaning “jealous” or “having the desire to own or dominate.” In a grammatical sense, it’s used as a noun or adjective referring to the ways in which possession (ownership) is shown in language.
Some grammatical concepts involving the word are possessive pronouns (e.g., “my”), possessive nouns (e.g., “Steven’s”), possessive apostrophes (apostrophes like the one in “Steven’s”), and possessive case (how words show possession in general).
You normally form a possessive noun from a singular noun by adding an apostrophe and an “s,” but there’s disagreement about how to form the possessive of a name like “James.”
Most style guides recommend adding the apostrophe and “s” like normal: James’s. But some argue that it should depend on which version feels most natural to pronounce, so that you could instead write James’, without the additional “s.”
We recommend the first approach, adding the “s” consistently, as it’s recommended by most authorities. Whatever you choose, be consistent about how you form the possessive of a particular name. Don’t write James’ at some points and James’s at others.
The plural of “moose” is the same as the singular: “moose.” It’s one of a group of plural nouns in English that are identical to the corresponding singular nouns. So it’s wrong to write “mooses.”
For example, you might write “There are several moose in the forest.”
Normally, the plural of “fish” is the same as the singular: “fish.” It’s one of a group of irregular plural nouns in English that are identical to the corresponding singular nouns (e.g., “moose,” “sheep”). For example, you might write “The fish scatter as the shark approaches.”
If you’re referring to several species of fish, though, the regular plural “fishes” is often used instead. For example, “The aquarium contains many different fishes, including trout and carp.”
The plural of “crisis” is “crises.” It’s a loanword from Latin and retains its original Latin plural noun form (similar to “analyses” and “bases”). It’s wrong to write “crisises.”
For example, you might write “Several crises destabilized the regime.”
A collective noun is any noun that is used to name a group of something (people, animals, things, etc.). “Group” is one very common collective noun. Collective nouns can be common nouns (like “group”) or proper nouns (like “Google” and other company names).
Collective nouns are most commonly treated as singular (e.g., “the herd is grazing”), but usage differs between US and UK English:
No, as a general rule, academic concepts, disciplines, theories, models, etc. are treated as common nouns, not proper nouns, and therefore not capitalized. For example, “five-factor model of personality” or “analytic philosophy.”
However, proper nouns that appear within the name of an academic concept (such as the name of the inventor) are capitalized as usual. For example, “Darwin’s theory of evolution” or “Student’s t table.”
The names of seasons (e.g., “spring”) are treated as common nouns in English and therefore not capitalized. People often assume they are proper nouns, but this is an error.
The names of days and months, however, are capitalized since they’re treated as proper nouns in English (e.g., “Wednesday,” “January”).
A proper adjective is an adjective that was derived from a proper noun and is therefore capitalized.
Proper adjectives include words for nationalities, languages, and ethnicities (e.g., “Japanese,” “Inuit,” “French”) and words derived from people’s names (e.g., “Bayesian,” “Orwellian”).
Common nouns are words for types of things, people, and places, such as “dog,” “professor,” and “city.” They are not capitalized and are typically used in combination with articles and other determiners.
Proper nouns are words for specific things, people, and places, such as “Max,” “Dr. Prakash,” and “London.” They are always capitalized and usually aren’t combined with articles and other determiners.
Pronouns are words like “I,” “she,” and “they” that are used in a similar way to nouns. They stand in for a noun that has already been mentioned or refer to yourself and other people.
Pronouns can function just like nouns as the head of a noun phrase and as the subject or object of a verb. However, pronouns change their forms (e.g., from “I” to “me”) depending on the grammatical context they’re used in, whereas nouns usually don’t.
There are many ways to categorize nouns into various types, and the same noun can fall into multiple categories or even change types depending on context.
Some of the main types of nouns are:
A noun is a word that represents a person, thing, concept, or place (e.g., “John,” “house,” “affinity,” “river”). Most sentences contain at least one noun or pronoun.
Nouns are often, but not always, preceded by an article (“the,” “a,” or “an”) and/or another determiner such as an adjective.
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