Sentence:  Club heads [of golf clubs] have weight distributions designed to optimize both launch angle of the ball and minimizing the effects of off-center shots that do not precisely impact the so-called <WSD>sweet spot</WSD> (the center of percussion). 
Meaning of the word marked with <WSD> tags:  Any of several places on a bat, racquet, etc., with which to hit a ball, resulting in the latter rebounding with some optimal desirable effect, such as minimum vibration or maximum velocity.