Official Definition:
“a sentence made from two independent sentences joined by ‘and’, ‘or’, or ‘but’, as in ‘Mary read and Tom slept.’ ”
"Compound Sentence." Cambridge Dictionary, Cambridge UP, 2022, dictionary.cambridge.org/dictionary/english/compound-sentence. Accessed 26 Aug. 2022.
Informal Definition:
A compound sentence is a sentence made up of two independent smaller sentences joined by a conjunction, and can be easily identified by the fact that a conjunction of two independent sentences will have a comma preceding the conjunction. For example: John walked to school, but James drove instead.
Etymology:
“borrowed from Late Latin complexus ‘composite, connected, intertwined,’ going back to Latin, past participle of complector, complectī ‘to embrace, grasp, encompass, include,’ from com- COM- + -plectī, deponent form of plectere ‘to plait, twine’ ”
"Complex." Merriam-Webster, Merriam-Webster, 2022, www.merriam-webster.com/dictionary/complex. Accessed 29 Aug. 2022.
Ben Pringle