What is "sole"ing a club?

[Tailgater]

Zach Johnson just had a tap-in. He was about to tap-in and then he quickly pulled his putter away. The announcer said, "He was careful not to sole his club." I know what grounding a club is. I have never heard of "sole"ing a club. And why is it illegal on the green?

[Asheville]

Zach Johnson just had a tap-in. He was about to tap-in and then he quickly pulled his putter away. The announcer said, "He was careful not to sole his club."

I know what grounding a club is. I have never heard of "sole"ing a club. And why is it illegal on the green?

Means the same as "grounding."

It's certainly not a breach to ground the club on the putting green. Who knows what the TV guy was referring to; we need some more information.

[Tailgater]

The only thing I can think of was that wind was blowing quite hard at address and he might have been afraid that the ball would move. Is that relevant?

[David in FL]

Sole = ground.... Nothing illegal, but if you ground (sole) the putter behind the ball and the ball subsequently moves, you're deemed to have caused it to move and are penalized.

[rogolf]

Sole = ground....

Nothing illegal, but if you ground (sole) the putter behind the ball and the ball subsequently moves, you're deemed to have caused it to move and are penalized.

Correct, except if it is known or virtually certain that something else (such as wind) caused the ball to move.  Exception added to Rule 18-2b in 2012.