complex sentence

noun

a sentence containing one or more dependent clauses in addition to the main clause, as When the bell rings (dependent clause), walk out (main clause).

noun

grammar a sentence containing at least one main clause and one subordinate clause

A sentence that contains one main clause or independent clause and at least one subordinate clause or dependent clause: “Although I am tired (subordinate clause), I want to go to the midnight movie (main clause).” (See subordination; compare compound sentence, compound-complex sentence, and simple sentence.)