ace /ās/

1. A unit
2. The one in dice, cards, dominoes, etc
3. A single point
4. A winning serve, esp one which the opponent fails to touch (tennis)
5. A hole in one (see under hole¹; golf)
6. A jot
7. A person of the highest character (Burns)
8. A person of distinguished achievement, an expert (orig an airman) (informal)

1. Of highest quality
2. Outstanding

1. To serve an ace against (an opponent) (tennis)
2. To play (a hole) in one stroke (golf)
3. To pass (an examination) with the highest available mark (US informal)

an ace up one's sleeve or an ace in the hole

A decisive but hidden advantage

hold all the aces

To have all the advantages, be in a winning position

play one's ace

To use one's best weapon, resource, etc

within an ace of

Within a hair's-breadth of

• underproduction
• under proof
• underproof
• underprop
• underpropped
• underpropping
• underprops
• under protest
• underquote
• underquoted
• underquotes
• underquoting
• underran
• under-rang
• underrate
• underrated
• underrates
• underrating
• under-report
• under-reported
• under-reporting
• under-reports
• under-representation
• under-represented
• under-ring