In Roman times an as was the name given to a small copper coin, possibly of Etruscan origin. The same word was also used to denote a ‘unit’ of weight, measure or coin. When as was borrowed into Old French in the twelfth century, it most commonly referred to ‘the side of a die marked with a single spot’, a meaning it retained when it was taken into Middle English as aas around the turn of the fourteenth century.
When playing cards became popular in France, as was applied to a card bearing one pip. Similarly, in the sixteenth century English used ace to denote a one-spot card, the English deck being modelled on the French. In a game of dice the one-spot had the lowest value and so, in Old French and then in English, ace had the figurative sense of‘nothing at all, valuelessness, bad luck’.
However, in many card games an ace rates high and this has led to a number of figurative uses with a positive sense: since the late nineteenth century it has been applied to ‘a point won in a single stroke in tennis or badminton’; in twentieth- century American colloquial English, and increasingly in British English, ace has been used as a noun to denote ‘a person who is particularly gifted at something’ and also as an adjective to mean ‘highly skilled’, or ‘of superior quality’; and since the First World War ace has described ‘a fighter-pilot who has shot down at least five enemy planes’.