Adjective contentious has 3 senses
- contentious, disputatious, disputative, litigious - inclined or showing an inclination to dispute or disagree, even to engage in law suits; "a style described as abrasive and contentious"; "a disputatious lawyer"; "a litigious and acrimonious spirit"
Antonym:  unargumentative (indirect, via argumentative)
 - contentious - involving or likely to cause controversy; "a central and contentious element of the book"- Tim W.Ferfuson
Antonyms:  uncontroversial, noncontroversial (indirect, via controversial)
 - battleful, bellicose, combative, contentious - having or showing a ready disposition to fight; "bellicose young officers"; "a combative impulse"; "a contentious nature"
Antonyms:  unaggressive, nonaggressive (indirect, via aggressive)
 
,