The term 'MERCURY ALIAS' refers to two different names for the same entity. The first alias is 'QUICKSILVER', which is an 11-letter word. This is a reference to the element mercury, which is also known as QUICKSILVER due to its silvery liquid form. The second alias is 'HERMES', which is a 6-letter word. This is a reference to the Greek god HERMES, who was associated with speed and travel, which are qualities of the element mercury.