A nominal clause is a clause (a group of words containing its own subject and verb) that is taking the place of a noun or pronoun in a sentence: Example: "I don't know [when I should arrive]." "[How he survived] is a mystery to me." A relative nominal clause has the same function, but begins with a relative pronoun: "[Whoever wants to come] is invited to my party." "I wonder [who left this package]."

Dictionary definition of a nominal clause 1. A clause functioning like a noun (or noun phrase). (Also called noun clause .) Nominal clauses, other than nominal relative clauses, tend to be abstract in meaning. A nominal clause can be a subject, object, or complement in sentence structure:[ What happened next ] remains a mystery (S)He alleges [ (that) he doesn't remember a thing ] (O)The question is [ how we should proceed ] (C) and can function in various other ways:I'm not sure [ if we should report this ] (complement of adjective)It depends on [ what happens next] ...