'observer-dependent' originates from Modern English, composed of the elements 'observer' and 'dependent'. 'observer' ultimately originates from Latin 'observare', where 'ob-' meant 'toward' and 'servare' meant 'to watch or keep'; 'dependent' ultimately originates from Latin 'dependere', where 'de-' meant 'down' and 'pendere' meant 'to hang.'

'observer' entered English via Old French 'observer' from Latin 'observare', and 'dependent' came via Old French 'dependre' from Latin 'dependere'; the hyphenated compound 'observer-dependent' is a modern English formation used to describe properties that rely on an observer or reference frame.

Initially, 'observer' meant 'one who watches' and 'dependent' meant 'hanging down or attached'; over time the compound evolved to mean 'relying on or varying with the observer's perspective or measurement context.'