'black-box' originates from English, specifically the words 'black' and 'box', where 'black' derives from Old English 'blæc' meaning 'dark' or 'burned', and 'box' derives from Old English 'box' (from Latin 'buxus') meaning 'a container or case'.

'black-box' began as a literal compound meaning 'a dark or black container'. In engineering and electronics in the early 20th century it came to mean a component whose internal workings were not examined; by the mid-20th century the term was applied to aircraft flight recorders and later broadened into computing and general use as a metaphor for any system with hidden internals.

Initially it referred to a literally 'black' or closed container; over time it evolved into the technical/metaphorical sense of 'a system with hidden or unknown internal workings' and also acquired a specialized sense as the name for aircraft flight recorders.