'rigorously' originates from Latin, specifically the word 'rigor,' where 'rigor' meant 'stiffness or strictness.' 'Tested' comes from the Latin word 'testari,' meaning 'to witness or affirm.'

'rigor' transformed into the Old French word 'rigour,' and eventually became the modern English word 'rigor.' 'Testari' evolved into the Old French 'test,' which became 'test' in Middle English.

Initially, 'rigor' meant 'stiffness or strictness,' but over time it evolved into its current meaning of 'thoroughness.' 'Test' originally meant 'to witness or affirm,' and now means 'to evaluate or examine.'