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.
Meaning strong horizontal beam is from c.1600. Meaning dormant or inoperative thing is from 1620s. Meaning railroad sleeping car is from 1875. Sense of something whose importance proves to be greater than expected first attested 1892, originally in American English sports jargon, probably from earlier (1856) gambling slang sense of unexpected winning card.