One-Suited Hand
Points-Showing Double

When partner makes a conventional bid (normally 2C or Dbl) over 1NT to show a one-suited hand, and the next player bids, a double shows a willingness to compete -- at least 8 HCPs and at least a doubleton in the unbid suits. (If RHO has made an artificial bid, such as a transfer, the "unbid" suits are all the others except his real suit, rather than the suit he actually bid.)

For more information, see ACBL Bulletin, Nov. 2005, page 49.