"The word "ace" comes from the Old French word as (from Latin 'as') meaning 'a unit', from the name of a small Roman coin. It originally meant the side of a die with only one mark, before it was a term for a playing card. Since this was the lowest roll of the die, it traditionally meant 'bad luck' in Middle English, but as the ace is often the highest playing card, its meaning has since changed to mean 'high-quality, excellence'. "