You could look at just about any line in "The Raven" and find descriptive language. The poem is packed with adjectives, imagery, and words that create mood.
The opening lines say, "Once upon a midnight dreary, while I pondered, weak and weary, /Over many a quaint and curious volume of forgotten lore—" (lines 1-2). Already in these first two lines there are 6 adjectives used: "dreary," "weak," "weary," "quaint," "curious," and "forgotten." All of these words are descriptive language that tell the reader the night is dismal, the narrator is tired and weak, and the books he's reading are strange and obscure.
In line 11, the narrator uses "rare" and "radiant" to describe his lost love, Lenore. In contrast to his weak, sad existence, she was the thing that was beautiful and hopeful.
When the Raven arrives in the narrative, he is also given a lot of description. The narrator calls him "ebony" (line 43), "stately" (line 38), "grave and stern" (line 44), and "ghastly grim and ancient" (line 46). There is an abundance of adjectives about the Raven that emphasize his seriousness and creepiness.
You could find dozens of examples of descriptive language throughout this poem, but these are some of the words that describe the three main figures.