The misuse of epic has long been a pet peeve. As a noun, an epic is an extended narrative poem celebrating the feats of a legendary or traditional hero. It can also be a long film, book, or other work portraying heroic deeds and adventures or covering an extended period of time.
As an adjective, epic means heroic or grand in scale or characteristic of an epic. It can also mean impressive or remarkable. This usage gives me the most grief. As I tell my son, every activity of the day can’t be epic. By overusing adjectives such as epic, one dilutes their meaning.
In addition to epic, here are some other adjectives (and a few adverbs) that have lost their meaning through overuse or misuse.