"Cowardice, as distinguished from panic, is almost always simply a lack of ability to suspend the functioning of the imagination." [Ernest Hemingway, "Men at War," 1942]
An O.E. word for "cowardly" was earg, which also meant "slothful."
"Yit had I levir do what I may Than here to dye thus cowerdelye" ["Le Morte d'Arthur," c.1450]
"I should explain to your Lordship what is meant by crackers; a name they have got from being great boasters; they are a lawless set of rascalls on the frontiers of Virginia, Maryland, the Carolinas and Georgia, who often change their places of abode." [1766, G. Cochrane]