Arbitrary

Arbitrary (Adjective): .Based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something

“In my own experiences as a student, I have enjoyed voluntary, informal collaborations with my friends, but I have resented being forced into arbitrary, mismatched teams in the name of social correctness,” this is where I encountered the word.

http://elupton.com/2009/10/why-collaborate/

When I first encountered the word arbitrary, I used context clues but I still did not understand the word. I then searched up the term on www.merriam-webster.com and got its definition. Two definitions came up, but the second one was most appropriate. However, the definition basically means by random selection or random choice. The author of the article is voicing her opinion on random selections of groups. She is saying that she dislikes arbitrary because she will feel more comfortable, with a group that she selected rather than one that was forced upon her.