The phrase "grow dull" is often used to describe a decrease in brightness, sharpness, or liveliness. The antonyms for this phrase include brighten, sharpen, enliven, invigorate, refresh, liven up, animate, rejuvenate, revitalize, and stimulate. These words indicate a sense of renewal and revitalization, suggesting an exciting and uplifting experience. By using antonyms for "grow dull," we can add a sense of energy and excitement to our language, allowing us to better express ourselves and convey meaning. Whether we're speaking or writing, using these antonyms can help us create a more engaging and dynamic conversation or story.