covetous
Having a greedy, jealous desire for something someone else owns.
Covetous means having a strong, greedy desire for something that belongs to someone else. A covetous person doesn't just admire their friend's new bike or wish they had one like it: they want that specific bike, the one their friend owns.
The word carries a sense of unhealthy longing. When you're covetous, you focus so much on what others have that you forget to appreciate what you already possess or to work toward your own goals. A student might feel covetous of a classmate's art talent instead of developing their own skills. A covetous neighbor might obsess over someone else's beautiful garden rather than planting their own flowers.
The related word covet is the verb form: “She coveted her sister's success.” Being covetous is different from healthy ambition or admiration. Ambition drives you to achieve your own goals, while being covetous traps you in jealous thoughts about what others have achieved or acquired.