'prohibitory' originates from Latin, specifically the Late Latin word 'prohibitorius', where 'pro-' meant 'forward/away' and 'habēre' (via 'hibere') meant 'to hold' or 'to keep.'

'prohibitory' changed from Late Latin 'prohibitorius' into Medieval/Old French forms (e.g. 'prohibitorie') and entered Middle English as 'prohibitory', eventually becoming the modern English adjective 'prohibitory'.

Initially, it meant 'serving to keep away or to hold back' in a literal and legal sense; over time it evolved into the broader modern sense of 'forbidding' or 'tending to prevent.'