'decisively-built' originates from the combination of 'decisively' and 'built'. 'Decisively' comes from the Latin word 'decidere', meaning 'to decide', and 'built' is the past participle of 'build', which comes from the Old English 'byldan'.

'decidere' transformed into the Old French 'decider', and eventually became the modern English word 'decide'. 'Byldan' evolved into the modern English 'build'.

Initially, 'decidere' meant 'to cut off', but over time it evolved into its current meaning of 'to make a decision'. 'Byldan' has largely retained its meaning of 'constructing or forming something'.