For starters, we need a definition for gesture drawings. Though there isn’t a specific entry in most dictionaries, here is the heart and soul of it:
A gesture drawing is usually a quick, often simple drawing that captures the essential feeling, energy, movement, action, or pose of the subject. It contains a minimum amount of information (line, tone, markings) to achieve the maximum results of the essence of the subject. It can be realistic, but is not always. It does not try to capture anything “photo-realistically” but instead alters reality down to its purest form to tell the story of the scene being drawn.
Since we work in a visual medium, the best thing to do is take a look at examples of gesture drawings: