If "shine" refers to emitting light:
* Dim
* Darken
* Obscure
* Dull
* FADE
* Extinguish
If "shine" refers to being bright or brilliant:
* Dull
* Tarnished
* Dim
* Bland
* Mediocre
* Unremarkable
If "shine" refers to excelling or being successful:
* Fail
* Flounder
* Stumble
* Underperform
* Lag
* Struggle
If "shine" refers to reflecting light:
* Absorb
* Diffuse
* Scatter
* Matte
It's essential to consider the specific context to choose the most fitting antonym.