From The Art and Popular Culture Encyclopedia
Envy is an emotion that "occurs when a person lacks another’s superior quality, achievement, or possession and either desires it or wishes that the other lacked it." At the core of envy seems to be an upward social comparison that threatens a person's self-esteem: another person has something that the envier considers to be important to have. However, what is envied could also be something that is only of personal importance to the envier, even if what the other person has is of little significance in his or her society, or even seen as a sign of inferior status. If the other person is perceived to be similar to the envier, the aroused envy will be particularly intense, because it signals to the envier that it just as well could have been him or her who had the desired object. Salovey, P., & Rodin, J. (1984). Some antecedents and consequences of social comparison jealousy.
The word jealous is often used to describe an envious state. In its correct usage, jealousy is the fear of losing something to another person (a loved one in the prototypical form), while envy is the pain or frustration caused by another person having something that one does not have oneself.
In some cultures, envy is often associated with the color green, as in "green with envy". The phrase "green-eyed monster" refers to an individual whose current actions appear motivated by envy. This is based on a line from Shakespeare's Othello.
Envy (Invidia) is one of the Seven Deadly Sins.