gesticulation

It is commonly supposed that they communicated by sounds and tentacular gesticulations; this is asserted, for instance, in the able but hastily compiled pamphlet (written evidently by someone not an eye-witness of Martian actions) to which I have already alluded, and which, so far, has been the chief source of information concerning them.

The breeze had died away and the tree was now quite motionless save when William's statements required forcible gesticulations, which made it sway in a gentle nodding manner as though it were confirming every word the old sage uttered.