The term 'slowly-controlled' is a compound word formed from 'slowly' and 'controlled'. 'Slowly' originates from Old English 'slāwlice', meaning 'in a slow manner', and 'controlled' comes from Old French 'contreroller', meaning 'to check or verify'.

'Slowly' evolved from Old English 'slāwlice', while 'controlled' evolved from Old French 'contreroller', eventually forming the modern English compound 'slowly-controlled'.

Initially, 'slowly' meant 'in a slow manner', and 'controlled' meant 'to check or verify'. Together, they evolved to mean 'controlled in a gradual or deliberate manner'.