'item-dependent' is a compound formed from 'item' + 'dependent'. 'item' (as 'a separate thing or entry') ultimately comes via Middle English from Latin 'item' (originally meaning 'likewise' but later used for 'also' and as a list-term), and 'dependent' comes from Latin 'dependēns'/'dependere' (from 'de-' + 'pendere') where 'pendere' meant 'to hang'.

'dependent' developed from Latin 'dependere' to Medieval/Old French forms and entered Middle English as 'dependent' with the sense 'relying on or hanging from', while 'item' shifted from Latin list-use to a sense of 'individual thing' in Medieval Latin and Middle English; combining them in modern English created the compound 'item-dependent' to describe something that varies by item.

The parts initially carried senses of 'individual thing' ('item') and 'hanging/relying' ('dependent'); combined, they have retained a straightforward modern meaning of 'depending on the particular item' with little semantic shift beyond compounding.