ace [ME] An ace was originally the side of a dice marked with one spot. The word comes from Latin as, meaning ‘unit’. Since an ace is the card with the highest value in many card games, the word often suggests excellence. This gave us the ace as a wartime fighter pilot who brought down many enemy aircraft, used from the First World War and soon extended to anyone who excels at something. An ace up your sleeve [M19th] (or in American English an ace in the hole) is a secret resource ready to use when you need it. A cheating card player might well hide an ace up their sleeve to use at an opportune moment. To hold all the aces [E19th] is to have all the advantages, from a winning hand in a card game. To be within an ace of doing something [L17th] is from the ace as one and thus a tiny amount.