Noah Webster's New International Dictionary of the English Language

1. (v.) To make sharp.

2. (v.) To give a keen edge or fine point to; to make sharper; as, to sharpen an ax, or the teeth of a saw.

3. (v.) To render more quick or acute in perception; to make more ready or ingenious.

4. (v.) To make more eager; as, to sharpen men's desires.

5. (v.) To make more pungent and intense; as, to sharpen a pain or disease.

6. (v.) To make biting, sarcastic, or severe.

7. (v.) To render more shrill or piercing.

8. (v.) To make more tart or acid; to make sour; as, the rays of the sun sharpen vinegar.

9. (v.) To raise, as a sound, by means of a sharp; to apply a sharp to.

10. (v. i.) To grow or become sharp.