köken: From Middle High German briz (14th c.). This late and singular attestation allows no certainty about the quality of the vowel or the final alveolar. Origin unknown. Possibly related with Proto-Germanic *breustą (“breast”) or *breutaną (“to crush”). Compare also English brisket, whose -k- does not fit with the German form, however. Danish brissel, Swedish bräss (“thymus”) are probably from German.
köken: Diminutive of anima, initially figuratively used to indicate this offal cut being quite soft and delicate. Although the singular form animella exists in dictionaries, it is almost never used.