Argument; conflict (12)
I believe the answer is:
disagreement
I believe this is a double definition.
'argument' is the first definition.
(a disagreement is an argument)
'conflict' is the second definition.
(I know that disagreement is a type of conflict)
(Other definitions for disagreement that I've seen before include "Conflict" , "dispute" , "Difference of opinion" , "Quarrel" , "Argument" .)