Abhor is a bit of an antiquated phrase meaning that you strongly don't like something (example: I abhor my job, and I want to quit it right now). It is not really used much in normal conversation, but you often find it among older, more upper-class, or more poetic speech. If you want to have a more unique vocabulary, I would recommend it, but if you use it in a casual setting it can sound weird. Don't worry too much though, it's not offensive or anything as long as you use it to show an extreme dislike for something (you usually wouldn't say: "I abhor it when you eat with your mouth open" because this seems extreme for something so small). Here are some synonyms that are used more often and sound more casual:
hate
despise
loathe
And here are some that are less intense:
dislike
don't like
am annoyed by
Hope that helps!