Would a relationship be considered ''abusive'' if random unkind words are spoken during arguments or a pattern of repeated episodes for no reason?

There is no such thing "as no reason." Instead of arguing go to a coffee shop or a public place where you can have a little privacy and discuss what problems there could be in your relationship. Sometimes people aren't well, on certain medications that can change the personality, or depressed and don't realize it. They simple could be over-worked either in the workplace or at school. People act out their frustrations in different ways and it's important to try and communicate and try to help in any way you can. If you try and they won't work it out with you then you are going to have to make the decision as to whether it's worth it for you stay in the relationship. Good luck!