'starch-accumulating' is a modern English compound formed from 'starch' + the present-participle form of 'accumulate'. 'Starch' comes ultimately from Old English 'stearc' (meaning 'stiff'), while 'accumulate' comes from Latin 'accumulare' ('ad-' + 'cumulus', meaning 'to heap up').

'starch' originally referred to 'stiffness' in Old English and later came to denote the substance that stiffens (the carbohydrate). 'Accumulate' entered English via Late Latin and Old French from Latin 'accumulare' and developed into the modern verb meaning 'to gather or heap up'; combining them as a compound adjective is a recent, descriptive formation in scientific and technical contexts.

Initially, 'starch' meant 'stiffness' and later the substance responsible for that property; 'accumulate' originally meant 'to heap up' in the literal sense and evolved to mean 'collect or build up' more generally. The compound now specifically describes the process or state of gathering starch.