名詞 dimmer:

1. a rheostat that varies the current through an electric light in order to control the level of illumination

形容詞 dim:

1. lacking in light; not bright or harsh
   同義詞：dim, subdued
2. lacking clarity or distinctness
   同義詞：dim, faint, shadowy, vague, wispy
3. made dim or less bright
   同義詞：dimmed, dim
4. offering little or no hope
   同義詞：black, bleak, dim
5. slow to learn or understand; lacking intellectual acuity
   同義詞：dense, dim, dull, dumb, obtuse, slow

dim.mer

n.（名詞）
A rheostat or other device used to vary the intensity of an electric light.
調(diào)光器：使電燈光減弱的一種變阻器或其它裝置

A parking light on a motor vehicle.
汽車上的停車燈
Low beam.
車頭的短焦距光