Bagel

A bagel is a set won 6-0. The zero looks like a bagel, and that is the whole joke. A 6-0, 6-0 match is a double bagel; a 6-0, 6-0, 6-0 win in a best-of-five match, the shortest complete match possible, is a triple bagel. The 6-1 cousin is a breadstick, the "1" being the breadstick.

The word is credited to the American players Harold Solomon and Eddie Dibbs and was popularised by the commentator Bud Collins, according to the term's Wikipedia entry.

When you see it

A bagel means the loser did not win a service game in the set, so it usually turns up in early rounds when a top seed meets a qualifier or a wild card, or when one player is carrying an injury. It says nothing about points: a 6-0 set can contain several deuce games. A set in which the loser wins no points at all is the far rarer golden set. Players use the word freely; you will hear "I got bagelled" in press conferences.

Rule basis

Not a rulebook term. A set is won by the first player to six games with a two-game margin (ITF Rules of Tennis, Rule 6), and 6-0 is simply the shortest way there.