Poem of nonsense verse by Lewis Carroll that begins "'Twas brillig, and the slithy toves/Did gyre and gimble in the wabe" (11)
I believe the answer is:
jabberwocky
(Other definitions for jabberwocky that I've seen before include "Lewis Carroll nonsense poem" , "Nonsense poem in Lewis Carroll's Through the Looking Glass" , "Lewis Carroll poem from "Through the Looking Glass"" , "Twas brillig poem" .)