eral Dictionaries] n., Collections of objects or elements that have at least one characteristic in common. For example, the set X may consist of all the elements x1, x2, x3, etc. This is written {x1, x2, x3,…} = X. [Sciences] 
 A fundamental, essential, or irreducible constituent of a composite entity. [General Dictionaries] 
n., An abbreviation of electronic mail, an Internet protocol that allows computer users to exchange messages and da
ta files in real time with other users, locally and across networks.