Why is no idea not a plural number?

No idea means negation, and negation is singular.

hear nothing of

Pronunciation: English [n ad] America [no? adi].

Interpretation: I don't know.

Idea basically means "idea" and is used as a countable noun. Idea can also be used in the academic field, meaning "concept" and "concept". Idea can also be used as a "know, understand" solution. When used in the latter two meanings, it can be used as both uncountable and countable nouns.

Idea is often followed by the preposition "of+ noun, pronoun, gerund or interrogative clause" as an attribute, or directly with that clause.

The same root phrase:

Understand someone's meaning.

Communicate an idea to exchange ideas.

Destroy an idea, get rid of an idea

Develop an idea to explain an idea.

Discuss an idea to discuss some opinions.

Immerse yourself in ideas and absorb them.

Hold an idea.

Exchange ideas, exchange ideas and opinions.

Explain an idea.

Express an idea to express an opinion.