hinge

11:18 Oct 31, 2014 

2. DON'T FEAR THE CUP
Although modern teaching standards call for a flat left wrist at the top, Rory actually cups his wrist a bit, which allows him to maintain a square clubface despite his strong left-hand grip. He also exhibits a full wrist hinge, evidenced by the fact that the shaft is near parallel to the ground (photo, above). This is impossible to do if you tense up at address. The secret is to make as full an upper body turn as possible while keeping your arms, wrists and hands loose and free to hinge the club up. Moreover, allowing your left wrist to cup instead of forcing it perfectly flat makes it easier to keep your left arm relaxed and to hinge your wrists to their maximum capacity. A flat left wrist sounds nice, but it can potentially lead to undue tension in your lead arm.
Read more: http://www.golf.com/instruction/learn-rory-mcilroys-swing-an...

09:43 Oct 31, 2014 

Wrists yes: ...take the club back along the line of your feet, and hinge your wrists to promote a steeper
plane (feel as if you are ‘picking the club up’).
Found in Gilou's reference.