A noun idiom is a unique noun phrase with a unique meaning. It can be…
NOMINALS
Nominals are words (such as pronouns and gerunds), phrases, or clauses which perform the functions of nouns.
Functions: subject, direct object, indirect object, predicate noun, object complement, object of a preposition, etc.
Kinds: There are six kinds of nominals in English:
- Pronoun, which can widely replace a noun (e.g. he, she, it, etc.)
- Gerund, which looks like a verb with -ing ending but functions as a noun (e.g.: Reading is my hobby.)
- Noun-infinitive, which also looks like a verb (mostly preceded by to) with present and perfect forms but acts as a noun (e.g.: To eat is good).
- Substantive, which is an adjective used as a noun (e.g.: The pure are happy).
- Noun Phrase, which is a group of words without a finite verb used as a single noun. (e.g.: A stitch in time saves nine).
- Noun Clause, which is a group of words having a subject and a finite verb used as a single noun (e.g.: That you are ignorant of the law is a flimsy excuse).