Definition: "Marginal Hand"

I can't seem to find the definition on my trusty poker lingo website. I'm fimiliar with the term 'marginal' in the subject of economics, but I doubt it is similar to it. Can someone help me?

Basically a hand which is neither especially 'good' nor especially 'bad', given the situation. The definition can change somewhat depending on the situation - for example AJs would be a 'marginal hand' UTG at a normal full table, but on the button when folded to and with tight blinds it becomes a lot more powerful because of the situation at hand.

Oh, then basically it's a modest pocket hand, factoring in the conditions of that hand...

I tend to think of it in terms of EV. A marginal hand is a hand that has an expected value of about 0. For instance, AJs UTG at a full table - I don't expect to show any huge profits with it in the long run, but I don't expect to be a significant loser either.

What's so interesting about marginal hands is that it's there that we can improve to find loads of money. Even a monkey can get it all-in with AA vs. KK, but as we get better we start to make better decisions in marginal spots. And that = $$.