The British spelling variant of 'familiarization'; the process of becoming familiar with something or making something familiar to someone.
From 'familiarize' (to make familiar) plus '-ation,' which is the British English spelling convention, versus American '-ization.' The root is Latin 'familiāris.'
The difference between British 'familiarisation' and American 'familiarization' is just spelling, but it shows how the same language split geographically and developed different conventions for word endings!
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