Most commonly used by responder to show an unbid major with a hand not suitable to bid the major directly (too short or too weak).

Examples

Opener Overcall Response Meaning
1♣ 1 Dbl 6+ points, exactly 4♠s (1♠ would show 5+♠s)
1♣ 1♠ Dbl 6+ points, 4+s (note the + here - it can show 5s (and weak), as there is no room for a comparable bid to 1♠ shown above)
1♣ 1 Dbl 6+ points, exactly 4-4 in the majors
1 2♣ Dbl 6+ points, at least one 4+ major
(can’t have 5 card major and 10+ points)
1 2 Dbl 4♠s and 6+ points OR 5+♠s and 6-9 points
(denies heart support)
1 1♠ Dbl 6+ points, at least 4-4 in the minors
(denies heart support)


Hearts Showing Negative Double

Note the double in this context shows 4+s

Minors Showing Negative Double


Misleading Negative Double

North’s double denies spade support

bridgebum source