define compound complex sentences
Also found in: Wikipedia. compound-complex sentence. Compound-complex sentences are one of the four main sentence structures. They are made up of two independent clauses (also known as main clauses) and one or more dependent clauses (or subordinate clauses). For a sentence to be considered compound-complex, at least one of the independent clauses must be a complex sentence (if it were to stand on its own). That is, it is made up of a dependent clause that is introduced and linked to the independent clause by a subordinating conjunction.