'vaguely-defined' originates from the Latin word 'vagus,' meaning 'wandering' or 'indeterminate,' combined with 'define' from Latin 'definire,' meaning 'to limit' or 'to determine.'

'vagus' transformed into the Old French word 'vague,' and eventually became the modern English word 'vague.' 'Definire' evolved into the Middle English 'definen,' leading to the modern English 'define.'

Initially, 'vague' meant 'wandering' or 'indeterminate,' but over time it evolved to mean 'not clearly expressed or defined.'