Abbreviation of the word "suspicious" or its
derivatives (e.g. suspect)
Initially used in the game Among Us to
communicate more concisely who was "suspicious" of being
the imposter. Since, it has become a meme of equal magnitude to bruh, pog and other widely overused words.
Its use is satirized to oblivion, and it has basically ceased to contain any meaning. People will say sus as an answer to anything or anyone, in any sentence, randomly yell it or add it as a meaningless adjective.