Can you think of any words that are mainly used in a certain phrase?

People talk about looking in every nook and cranny. The word nook is sometimes used elsewhere, but have you ever heard cranny being used in any other way? There are other words like this, but I am having trouble remembering them.

The word iota is sort of like this. It always seems to be used in a negative sense, like not caring one iota. Nobody talks about adding an iota of wine to a recipe.