I've always thought of cold calling as calling with very little (A high for instance or low board pair) because you think your opponent has less. It's not a slow play. think of it as calling with "cold" cards that have potential. I don't know what the definition is. But when I think of calling someone "cold" I think of calling a bet that you have little reason to call because the bettor is saying "I have a hand" and you're cold calling him saying "I know you don't have a hand, and even though I don't have Much of a hand, I think it's better."

Smooth calling is when you probably have the best hand with an active bettor in front of you. Instead of revealing the strength of your hand with a raise, you call. Smooth calling is a slowplay move. You can smooth call whether you opened the pot or not preflop. You have AK, and flop is AAx. Bet in front, you call. that's a Smooth Call.

I have not read any poker dictionaries, but that's how I interpret those terms.