ace

noun
  1. a playing card with a single spot, ranking highest or lowest in various games
  2. a person who is very skilled at something
  3. Usage: informal
  4. a serve in tennis that the opponent cannot return
  5. Usage: tennis
verb
  1. to perform very well on a test or in a situation
  2. Usage: informal
adjective
  1. excellent or outstanding
  2. Usage: informal

Examples