The definition of a compound sentence is a sentence with at least two independent causes that could each be their own sentence.
An example of a compound sentence is "I must go to sleep soon, since I'm getting up early in the morning."
A sentence consisting of two or more independent, coordinate clauses (Ex.: She drinks coffee, but he prefers tea)
Attributive form of compound sentence, noun.
A sentence of two or more coordinate independent clauses, often joined by a conjunction or conjunctions, as The problem was difficult, but I finally found the answer.