Definition of St John's bread in English:

St John's bread

noun

  • A fruit of the carob tree, Ceratonia siliqua ; (more fully "St John's bread tree", "†St John's bread's tree") the tree itself.

Origin

Mid 16th century; earliest use found in William Turner (d. 1568), naturalist and religious controversialist. After early modern German sanct Johans brodt, and variants.