Markedly decreased alertness, to the point that the sufferer is nearly unresponsive; only basic stimuli can provoke a reaction.
Example: A man lies in a hospital bed and ignores you, even when you call his name. Painful stimuli make him groan and withdraw briefly.
Grinnell, R. (2008). Stupor. Psych Central. Retrieved on April 28, 2015, from http://psychcentral.com/encyclopedia/2008/stupor/