Undercast

You get gored by a rhino right between the legs. The doctor has to pile on the plaster in order for you to heal. One type of undercast.

Another kind relates to making predictions. You're trying to guess how much profit a company will earn for the fourth quarter. You run your models and determine that $10 million makes sense. When the company's profit is announced, it comes in at $12 million. You undercast by $2 million.

The opposite of undercast is overcast. That situation means you overshot the mark and guessed a number that was too high.