Obviously it means "feeling attraction to someone who is of a higher value than you" but it seems that's subjective.

For instance, I like a guy who is facially more attractive than me, which is classic hypergamy. But he is also shorter than me by a few inches. We both have jobs (so same SES) and the same sense of humor. Would this be hypergamy? Half hypergamy?

What is your definition of hypergamy?