A playing card with a single pip, typically the highest-ranking card in a suit; someone who excels at a particular activity.
From Old French as meaning 'unit' or 'one', derived from Latin as meaning 'unity' or 'a copper coin'. The meaning evolved from 'one' on dice to the playing card, then to excellence in general.
It's fascinating how this word journeyed from ancient Roman coins to modern slang for excellence, carrying the mathematical concept of 'one' through centuries of gambling, aviation, and sports. The ace pilot of WWI gave us the modern meaning of mastery.
Complete word intelligence in one call. Free tier — 50 lookups/day.