'shiftable' originates from Modern English, formed from the verb 'shift' + the suffix '-able', where 'shift' conveyed the idea 'to move or change' and '-able' meant 'capable of'.

'shift' changed from Old English 'sciftan' (and is related to Old Norse 'skifta') into Middle English forms such as 'shiften' and eventually became the modern English verb 'shift'; adding the adjectival suffix '-able' (from Old French/Latin '-abilis') produced 'shiftable'.

Initially, the root meant roughly 'to divide, arrange, or change'; over time its sense shifted toward 'to move or change position', and 'shiftable' came to mean 'capable of being moved or changed'.