What is the noun form of "shimmer"?

The noun form of "shimmer" refers to a weak and tremulous light. This captures the essence of what it means to shimmer, which is characterized by a flickering or wavering quality rather than a steady or powerful brightness. The term evokes images of light that is not wholly stable but instead dances or moves in a delicate manner, much like the light reflecting off water or through a veil.

Other options describe different types of light but do not align with the characteristic qualities of a shimmer. A strong and radiant glow suggests brightness and intensity, while constant and bright illumination implies steadiness, both of which diverge from the subtler nature of shimmering light. Lastly, heat radiation refers to a physical phenomenon associated with warmth rather than a visual quality of light. Thus, the correct choice effectively embodies the unique, gentle flicker inherent in the concept of "shimmer."