Schtick is a Yiddish term that refers to a comic routine or gimmick used in a performance. Its antonyms would be seriousness, sobriety, gravity, and earnestness. If a performer is not using a schtick, then they are likely to be taking their performance seriously and approaching it with gravity and sobriety. While comedic performances can still be taken seriously, they will not utilize "schtick" as a gimmick or routine. Schtick is a unique term, and it is difficult to find antonyms as it has a specific meaning, but the opposite concepts would be seriousness and a lack of gimmicks in a performance.