Kendon, A. (2004). Gesture: Visible action as utterance. Cambridge, UK: Cambridge University Press.
From Chapter 2, “Visible action as gesture,” pp. 7-16.
Kendon begins with a very broad definition of utterance: “any ensemble of action that counts for others as an attempt by the actor to ‘give’ information of some sort” (p. 7). Kendon sees gestures as communicative, so gestures are the portion of the ensemble that occupies the visual channel. Importantly for Kendon, gestures must be communicative, not merely informative, so not all visible actions count as gesture: smiling, proxemics, practical actions, nervous movements, etc.
Gestures, are excursions of the articulators, with defined starting and stopping points, in which the movement is not merely the result of gravity acting on an articulator. Again, to Kendon, gestures are predominantly an aspect of communication, so we cannot simply define a particular movement as a gesture and claim it to be so in all contexts; instead we must consider which visible actions a listener might attend to a particular context as the visual portion of the speaker’s utterance.