1. (verb) to make the subject of dispute, contention, or litigation

• contend
• contest

1. (verb) to make the subject of dispute, contention, or litigation

• challenge
• dispute
• gainsay

1. (verb) to make the subject of dispute, contention, or litigation

• oppose

1. (verb) to make the subject of dispute, contention, or litigation

• arguing
• arguing
• argument
• argument
• contention
• contention
• contestation
• contestation
• controversy
• controversy
• disceptation
• disceptation
• disputation
• disputation
• tilt
• tilt
• contest
• contestable
• contestee
• contester
• incompatibility
• inconsistency
• mutual exclusiveness
• repugnance