A pilot who has shot down five planes or more
An expert in an activity
A person with a high degree of knowledge or skill in a particular field
Exceptionally good of its kind
To win a victory over, as in battle or a competition
He was back almost immediately, carrying an ace bandage.
Once an ace detective, always an ace detective.
"Sit still and I'll go get an ace bandage," he barked.
Six hundred rubles, ace, a corner, a nine... winning it back's impossible...