'decisively-formed' originates from the combination of 'decisively' and 'formed'. 'Decisively' comes from the Latin word 'decidere', meaning 'to decide', and 'formed' comes from the Latin 'formare', meaning 'to shape'.

'Decidere' transformed into the Old French word 'decider', and eventually became the modern English word 'decide'. 'Formare' transformed into the Old French word 'former', and eventually became the modern English word 'form'.

Initially, 'decidere' meant 'to cut off' or 'to decide', and 'formare' meant 'to shape'. Over time, these meanings evolved into the current usage of 'decisively-formed', meaning 'clearly defined'.