The Hebrew adjective bavli means 'Babylonian' — belonging to or characteristic of Babylon. It appears in Ezra and Daniel in reference to the Babylonian context of Israel's exile and the Babylonian officials, customs, and language that shaped that period.
The 'Babylonian' designation in Ezra and Daniel marks the crucible in which the Jewish identity was tested and refined. Daniel and his friends were given bavli names, taught bavli wisdom, and expected to assimilate into bavli culture — yet they maintained their covenant distinctives. This tension between cultural accommodation and covenant faithfulness is the permanent challenge of God's people living in any culture. The New Testament calls believers to be 'in the world but not of it' — engaging culture without losing identity.