'Barnaby' originates from Medieval English, specifically the name 'Barnabas', where 'bar' meant 'son' and 'naba' meant 'consolation'.

'Barnaby' changed from the Greek name 'Βαρναβᾶς' (Barnabas), which in turn came from the Aramaic phrase 'bar naba', and eventually became the modern English 'Barnaby' through Middle English usage.

Initially, it meant 'son of consolation', but over time it evolved into its current use as a male given name without the literal meaning being commonly considered.