[[]] (or in other words)
The is (to wipe) + (difficult to~). So when we say we are talking about that being something that it is difficult to wipe away. Next, do not think of as contempt. The words immediately following are rephrasing it. is just to treat something with little importance, or in other words, . I do not believe (someone please correct me if I'm wrong) that has any sort of enmity or ill will in it that you might find with a word like "contempt."
So would be a sort of undervaluing or disregard of words that is difficult to "wipe away," if we use the metaphor of the original. Ultimately the passage this is from is probably making a point about the importance of words.