Stiffness of the neck and resistance to passive movements, particularly flexion, usually accompanied by pain and spasm when motion is attempted.

It is recognized widely as the most common sign, after early infancy, of meningeal irritation, notably of meningitis and bleeding into the subarachnoid space which is the layer of tissue situated or occurring between the arachnoid (like a cobweb of fibers) and the pia mater (the delicate and highly vascular, blood vessels, membrane immediately investing [covering or enveloping] the brain and the spinal cord).