Don't change your mind if you picked A! Someone who is fickle -- always changing his or her mind -- might not be very reliable. But "fickle" stems from a word that describes someone much more troublesome. When English speakers centuries ago described someone as "ficol," they meant that the person was deceitful or dishonest. "Fickle" is probably a distant relative of the word "foe," which names someone who is even worse than deceitful. "Foe" means "enemy," and comes from the Old English word "fah," meaning "hostile."