Giants (from Latin and Ancient Greek) are beings of human appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. Some modern perception of giants as stupid and violent monsters, sometimes said to eat humans, while other giants tend to eat the livestock.
Most obvious changes are increased size (ranging from relatively normal-sized but big to huge to closer geological scale), strength and endurance. Generally, giants lack any real supernatural abilities, but they can have the same ability to learn as, for example, humans, and some have truly impressive powers.
My best guess at a general weakness of giants is tying up their legs and making them trip a la Empire Strikes Back. ... In norse mythology the Giants are defeated by the Gods because of wisdom, Giants are impulsive, another weak: goddesses. Giants are lustful and luxurious.
The origins of Giants is unclear, conflicting and sometimes disputed. Although their tapered ears bear a resemblance to that of mer, some scholars believe they actually share an ancestral relationships with the Nords, through the Atmorans.