(1):
(a.) Extreme or sudden and causeless; unreasonable; - said of fear or fright; as, panic fear, terror, alarm.
(2):
(a.) 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.
(3):
(n.) A plant of the genus Panicum; panic grass; also, the edible grain of some species of panic grass.
(4):
(a.) By extension: A sudden widespread fright or apprehension concerning financial affairs.