Someone combative likes to fight, whether with fists or words.
See the word combat in combative? That's a clue to this word's meaning. Since combat is a type of fighting — usually in war — anyone described as combative likes to fight or just can't help getting in fights. A frequent barroom brawler is combative, but so is someone who is always starting arguments. Using swear words and constantly contradicting people could be considered combative behavior. People who are combative are also often described as hostile, angry, or pugnacious.