Definition of Body Language

The Oxford English Dictionary (revised 2005) definition is:
"body language - noun - the conscious and unconscious movements and postures by which attitudes and feelings are communicated [for example]: his intent was clearly expressed in his body language."
The Oxford Business English Dictionary offers a slightly different definition. Appropriately and interestingly the Oxford Business English Dictionary emphasizes the sense that body language can be used as a tool, rather than it being an involuntary effect with no particular purpose:
"body language - noun - the process of communicating what you are feeling or thinking by the way you place and move your body rather than by words [for example]: The course trains sales people in reading the customer's body language."
The OED dictionary definition of kinesics - the technical term for body language - depends on the interpretation of 'non-verbal communication':
"kinesics - the study of the way in which certain body movements and gestures serve as a form of non-verbal communication."