1 If a lot of blood leaks out, it can cause a buildup of pressure in the brain because the brain is enclosed in the skull. There is no room for brain tissue to expand, and so the leaked blood can compress and kill important areas of the brain.  Hemorrhagic strokes tend to be more serious than ischemic strokes.
Horizontal definition, at right angles to the vertical; parallel to level ground. See more.
Physics, Optics. 1  any of the lines or streams in which light appears to radiate from a luminous body. 2  the straight line normal to the wave front in the propagation of radiant energy.  a stream of material particles all moving in the same straight line.