'overfamiliarity' originates from the prefix 'over-' meaning 'excessive' and the word 'familiarity' from Latin 'familiaritas', where 'familiaris' meant 'of a household, domestic'.

'familiaritas' transformed into the Old French word 'familiarité', and eventually became the modern English word 'familiarity', with 'over-' added to denote excessiveness.

Initially, it meant 'excessive closeness or intimacy', and this meaning has largely remained the same in modern usage.