'designatable' originates from Latin, specifically the word 'designare', where 'de-' meant 'completely' and 'signare' meant 'to mark.'

'designatable' developed from the verb 'designate' (Old French 'designer', from Latin 'designare') and was formed in Modern English by adding the adjectival suffix '-able' to indicate capability.

Initially related to the action 'to mark out' or 'to point out,' it evolved into the adjectival sense 'able to be designated' (capable of being specified or appointed).