Combine cucumber, tomatoes, onion, and black olives in a large bowl.
In a smaller bowl whisk together lemon juice, olive oil, oregano, dill, salt, and pepper. Pour dressing over vegetables and toss well to combine. Refrigerate for 1 hour.
Fold in feta cheese just before serving. Use as a dip with pitas, chips, or as a side dish with fish or chicken.
