The hydronym Szywra refers to the small river in the Warta basin flowing in the central part of Greater Poland. Although its name remained unclear for most of the researchers, it was believed to be of Pre-Slavic or Balto-Slavic origin. The paper reveals that these hypotheses were based on the wrong interpretation of the source material, and provides a new etymology for the name Szywra. Based on the critical analysis of all of the reachable records of names referring to the river Szywra, it has been proven that its Polish name is an adaptation of the former German name Schieferbach. Such a process was possible due to the long-term bilingual situation in the region of Greater Poland.