The original meaning of terrible was anything that causes terror. That meaning still applies, but mostly this is a word for anything really bad.
Terrible used to be reserved for things that caused fear and terror, but today we use the word to describe anything awful, lousy, or just plain bad. People like saying “That movie was terrible!” or “The Yankees are terrible!” If you get a D on a test, you might tell your friends the test (or teacher) is terrible. Or you might also say, “I am terrible at taking tests.”
exceptionally bad or displeasing
intensely or extremely bad or unpleasant in degree or quality
extreme in degree or extent or amount or impact
causing fear or dread or terror