Indistinct, hazy or unclear.
Not bright or colorful.
Not smart or intelligent.
Disapproving, unfavorable: rarely used outside the phrase take a dim view of.
To render dim, obscure, or dark; to make less bright or distinct
To make something less bright.
To deprive of distinct vision; to hinder from seeing clearly, either by dazzling or clouding the eyes; to darken the senses or understanding of.
To become darker.
Not explicit, relatively ambiguous.