He is not mentioned by Homer, but his story is given in the Aeneid of Virgil and other accounts, as a treacherous agent of the Greeks who misleads the Trojans, encouraging them to bring the Trojan Horse inside the city. He sometimes appears in art, usually being dragged into Troy as a captive, with the horse behind him.
^Σίνων, Henry George Liddell, Robert Scott, An Intermediate Greek-English Lexicon, on Perseus Digital Library
^σίνομαι, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library