a plant of the genus panicum; panic grass; also, the edible grain of some species of panic grass.-extreme or sudden and causeless; unreasonable; -- said of fear or fright; as, panic fear, terror, alarm.-a sudden, overpowering fright; esp., a sudden and groundless fright; terror inspired by a trifling cause or a misapprehension of danger; as, the troops were seized with a panic; they fled in a panic.-by extension: a sudden widespread fright or apprehension concerning financial affairs.