'banc' originates from Old French, specifically the word 'banc', where the Germanic root '*bank-' meant 'bench' or 'raised piece (of earth or wood)'.

'banc' changed from Old French 'banc' (and from Frankish/Germanic *bank-) and has parallels in Middle English forms and in the related word 'bank'; in modern English 'banc' survives chiefly in fixed expressions (e.g. 'en banc') and in rare dialectal uses.

Initially, it meant 'bench' or 'long seat'; over time the form 'bank' became the common English form for many senses (including 'financial institution' and 'river bank'), while 'banc' remained in restricted or specialized uses (legal phrase 'en banc', some dialectal senses).