MOYSIAN FIT: A contract in which declarer’s trump suit is divided 4-3, usually thus described when the selection is made deliberately. Named for Alphonse Moyse Jr., whose ardent advocacy of this choice was part of his case in favor of opening four-card majors and raising with three trumps.
West’s opening bid was a standard weak two in hearts – promising a six-card suit and about 6-10 points. North felt that he had to do something with his strong hand and so chose to make a takeout double. South’s jump to three spades was invitational in the suit while denying a heart stopper (with a heart stopper and four spades he would have bid a Lebensohl 2NT at his first turn then continued with 3♠ over North’s forced 3♣ rebid).