COMB in ADJ-GRADED-hearted combines with adjectives such as `kind' or `cold' to form adjectives which indicate that someone has a particular character or personality or is in a particular mood.
They are now realising just how much they owe to kind-hearted strangers...
That Harriet is a cold-hearted bitch...
I tried to be light-hearted.
English dictionary. 2008.