Grows darker

• Turns down, as a light
• Turns down, as a bulb's wattage
• Turns down the lights
• Lowers, like the lights
• Becomes faint
• Keeps getting darker
• Sets mood lighting
• Turns down, as lights
• Turns the lights down

Wiktionary Word definitions in Wiktionary
vb. (en-third-person singular of: dim )