'unfamiliarize' originates from the prefix 'un-' meaning 'not' and the word 'familiarize' which comes from 'familiar', derived from Latin 'familiaris', meaning 'of a household, domestic'.

'familiarize' evolved from the Latin word 'familiaris' through Old French 'familier' and eventually became the modern English word 'familiarize'.

Initially, 'familiarize' meant 'to make known or acquainted', and 'unfamiliarize' evolved to mean 'not made known or acquainted'.