dim down
[for the lights] to go dim. The lights dimmed down for a few seconds. Open the stage curtain when the house lights dim down.
dim out
[for a light] to grow dim and go out altogether. The lights dimmed out twice during the storm. I was afraid that the lights would dim out completely.
dim something down
to make lights dim; to use a dimmer to make the lights dimmer. Why don't you dim the lights down and put on some music? Let me dim down the lights and put on some music.
dim something up
to use a dimmer to make the lights brighter. (Theatrical. A dimmer is a rheostat, variable transformer, or something similar. The expression, a seeming contradiction, is the opposite of dim something down.) As the curtain rose, the electrician dimmed the lights up on a beautiful scene. You dimmed up the lights too fast.
take a dim view of someone or something
to disapprove of someone or something. Of all the boys, the teacher likes Dave the least. She takes a dim view of him. I take a dim view of that law.