Which emotion is associated with the idiom, 'green-eyed monster'?

The term 'green-eyed monster', meaning jealousy, first appeared in Shakespeare’s Othello (1596), when Iago says, "Beware of jealousy, my lord! It’s a 'green-eyed monster' that makes fun of the victims it devours". Shakespeare used this term again in 'Merchant of Venice' (1605), when Portia says, "How all the other passions fleet to air, as doubtful thoughts, and rash-embraced despair, and shuddering fear, and 'green-eyed jealousy'!" As this metaphor suggests, jealousy is closely associated with the theme of ego, insecurity and reality.

Some experts have postulated that 'green-eyed monster' refers to the color associated with sickness, possibly because people's skin sometimes takes on a slightly yellow/green tinge when they are gravely ill. Jealousy generally refers to the thoughts or feelings of insecurity, fear, and concern over a relative lack of possessions. However, jealousy can consist of one or more emotions such as anger, resentment, inadequacy, helplessness or disgust.

Jealousy is a typical experience in human relationships, and it has been observed in infants as young as five months. Throughout history, artists have also explored the theme of jealousy in photographs, paintings, films, songs, plays, poems, and books, and theologians have offered religious views of jealousy based on the scriptures of their respective faiths.