Let's break this down some more. The definition of persuasive is ‘tending to persuade', and not much help in our analysis, so we look at the word persuade. This is defined as: "to move by argument, entreaty, or expostulation to a belief, position, or course of action". So now we have added action to our definition. The action needs an object which we know is the audience or in singular a viewer. When I put it all together I have a definition that reveals the true powerful nature and purpose of the presentation. A presentation is a persuasive account for the attention of the mind to move the viewer to action.
How many of us think of presentations in this way? My guess is not many. Most business people get assigned the task of creating a presentation to communicate some knowledge to some group of employees or partners or prospects and then dump a bunch of data onto a bunch of slides (usually too much of both). We meet the deadline, but have persuaded no one to do anything. If, instead, we set out to construct a communication that moves the viewer to action and we keep this in mind with every image, word, animation and font we add to the slides, and then we will be on the path to creating a great presentation. Of course this is no guarantee that the presentation will be persuasive or will hold anyone's attention, but those are topics for another day.