Syn or SYN may refer to: In arts and entertainment In music The Syn, a band Synyster Gates, lead guitarist of the band Avenged Sevenfold Fictional characters Doctor Syn, in novels by Russell Thorndike Other uses in arts and entertainment SYN Media, a youth media organization based in Melbourne, Australia In science and technology Syn addition, in organic chemistry Syn conformation in alkane stereochemistry Synonym (taxonomy), a system of accepted alternative names for species SYN (TCP), synchronise packet in transmission control protocol (TCP) Synchronous idle (␖), one of the C0 and C1 control codes SYN (OSC), a standardized namespace within Open Sound Control Other uses Syn (goddess), in Norse mythology Coalition of Left, of Movements and Ecology (Synaspismós, abbreviated SYN or ΣΥΝ), a Greek political party