I like how you defined jealousy. When I first read the question "What do I think jealousy is?", I was at a loss. I know I have felt jealous throughout my life, at different times, but I never really thought about what that meant. I never recognized a reason for being jealous, I just felt those intense negative thoughts and feelings of insecurity, anxiety, and fear about a potential or anticipated loss of someone or something I valued, as you so aptly defined it! Now with your definition, I can see and understand better those situations in which I felt jealousy. Amazing how such few words can open one's eyes (and heart), bring about an understanding that was not there before.
I wish I could have commented before you posted your definition, but as I said, I was at a loss. I had no idea how to define jealousy without going to a dictionary and giving you that definiton. I do admit, I have a jealous bone...I am human.