successful
Achieving your goal or getting a good result.
Successful means achieving something you worked toward or wanted to accomplish. When you set out to build a treehouse and finish it, you've been successful. When a scientist spends years researching a cure and finally discovers it, she's successful. When your soccer team practices hard all season and wins the championship, that's a successful season.
Success doesn't always mean being the best or winning first place. A successful project might be one where you learned new skills, even if it didn't turn out perfectly. A successful friendship is one where both people feel valued and supported. A successful business makes enough money to keep operating and serving its customers.
The word describes both the outcome and the person who achieves it. We call someone a successful inventor if their inventions work and people use them. We call a restaurant successful if customers enjoy the food and keep coming back.
What counts as success depends on what you're trying to do. For a farmer, a successful harvest means growing enough healthy crops. For a student, a successful study session might mean finally understanding a difficult math concept. Success means you set a goal, worked at it, and reached it or came meaningfully close to reaching it.