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Erroneous
Factually Unsound
Use 'erroneous' when you want to emphasize that something is not just wrong, but lacks factual correctness. 
Carefully Considered
The word 'erroneous' suggests a careful conclusion has been reached that something is incorrect, not merely an offhand remark. 
Objective Error
'Erroneous' is often used when pointing out objective mistakes, rather than subjective opinions. 