Definitions for "Chiasmus"
An inversion of the order of words or phrases, when repeated or subsequently referred to in a sentence
an inversion of the second of two parallel phrases; an inverted relationship between the syntactic elements of parallel phrases; e.g., "Men do not quit playing because they grow old; they grow old because they quit playing" (Oliver Wendell Holmes).
(COD 8) inversion in the second of two parallel phrases of the order followed in the first (eg. to stop too fearful and too faint to go)