What is the meaning of jealous?

adjective

• Showing extreme cupidity; painfully desirous of another's advantages.
  • usage: "he was never covetous before he met her"; "jealous of his success and covetous of his possessions"; "envious of their art collection"
  • synonyms: covetous, envious
• Suspicious or unduly suspicious or fearful of being displaced by a rival.
  • usage: "a jealous lover"
  • synonyms: green-eyed, overjealous