'poorly-defined' originates from the combination of 'poorly,' meaning 'in a poor manner,' and 'defined,' meaning 'clearly marked or outlined.'

'Poorly' and 'defined' have been used separately in English since the Middle Ages, but their combination into 'poorly-defined' is a more modern usage.

Initially, 'defined' meant 'to set boundaries,' but in combination with 'poorly,' it evolved to mean 'lacking clear boundaries or clarity.'