"subjective" refers to when the meaning or interpretation of something is dependent on a person's personal opinion. For example: "The value of a pet is subjective," which means that some people may really benefit from having a pet and think that pets are valuable, whereas other people may not. The word "subjective" is an adjective.

It's an adjective, so: How ones feels about the matter is subjective rather than objective. Opinions are always subjective since they are only one person's view.