Fallacious (5)
'fallacious' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for wrong that I've seen before include "Erronious" , "Erroneous" , "Injury - incorrect" , "Incorrect, illegal or immoral" , "Not correct" .)
'fallacious' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for untrue that I've seen before include "Fallacious" , "Wrong" , "Counter-factual" , "disloyal" , "Spurious" .)
'fallacious' is the definition.
(I know that fallacious can be written as unsound)
This is all the clue.
(Other definitions for unsound that I've seen before include "Not strong or free from defect - perhaps evidence in court" , "Unreliable, not well" , "Not reliable, like some evidence" , "Fallacious (argument)" , "Lame" .)