Sentence:  The breeze had died away and the tree was now quite motionless save when William's statements required forcible <WSD>gesticulations</WSD>, which made it sway in a gentle nodding manner as though it were confirming every word the old sage uttered. 
Meaning of the word marked with <WSD> tags:  A gesture; a motion of the body or limbs when speaking, or in representing action or passion, and enforcing arguments and sentiments.