1. too mature; having matured beyond an ideal or desirable point
2. (of fruit, grain, or other produce) ripened excessively; no longer at peak quality

Examples

• The overmature bananas had brown spots and were too soft to eat.
• The wine had become overmature and lost much of its flavor.
• Overmature cheese can develop an unpleasant taste.
• The overmature grain was no longer suitable for milling.
• She felt the performance was overmature in its themes for a young audience.