dim

Lacking in light; not bright or harsh.

“a dim light beside the bed”

Slow to learn or understand; lacking intellectual acuity.

“never met anyone quite so dim”

Lacking clarity or distinctness.

“a dim figure in the distance”

Offering little or no hope.

“took a dim view of things”

Made dim or less bright.

“the dimmed houselights brought a hush of anticipation”

“dimmed headlights”

Make dim or lusterless.

“Time had dimmed the silver”

Switch (a car's headlights) from a higher to a lower beam.

Make dim by comparison or conceal.

Become vague or indistinct.

Become dim or lusterless.

“the lights dimmed and the curtain rose”