The underlined portion "Cynthia's Brow" is an example of a metaphor. It is comparing someone's brow to that of Cynthia's, using it to describe the appearance or characteristics of that person's brow.
alliteration
personification
allusion
Please provide the specific passage from "Huckleberry Finn" with the underlined portion for me to identify the literary term contained within it.
the devil
allusion
metaphor
oxymoron
simile
it's hard
personification
alliteration