'auspex' originates from Latin, specifically the word 'auspex' (genitive 'auspicis'), where 'avis' meant 'bird' and 'specere' meant 'to look.'

'auspex' passed through Classical Latin into Medieval Latin and was later borrowed into English; related words such as 'auspice' and the plural 'auspices' developed from the same Latin root during the word's transmission into medieval and later English.

Initially, it meant 'one who watches birds' (a bird-observer); over time it came to mean more generally 'an augur or interpreter of omens,' and through related forms (e.g. 'auspice') acquired the additional figurative sense of 'guidance or support.'