'Chiasmus' definitions:

Definition of 'chiasmus'

noun

Inversion in the second of two parallel phrases

From: GCIDE

Chiasmus \Chi*as"mus\ (k[-i]*[a^]z"m[u^]s), n. [NL., fr. Gr. chiasmo`s a placing crosswise, fr. chia`zein. See Chiasm.] (Rhet.) An inversion of the order of words or phrases, when repeated or subsequently referred to in a sentence; thus, [1913 Webster]
If e'er to bless thy sons My voice or hands deny, These hands let useful skill forsake, This voice in silence die. --Dwight. [1913 Webster]