synchysis (SIN-ki-suhs) - n., a parallel structure in the order of words in two phrases; any linguistic structure with an A-B-A-B pattern; (rhet.) a confused arrangement of words in a sentence, such as an inversion taken to extreme.
I like chiasmus, for chiasmatic structures are likeable. "He knowingly led and we followed blindly." It's useful all sorts of way for binding phrases together and highlighting that they are bound. It's also capable of quite subtle effects, such as when used as a pattern of alliteration binding four key words together without being obvious about it by alliterating all four on the same sound. The name comes from the Greek letter chi, written Χ -- and why becomes clearer when you write the schema thus:
A B \/ /\ B A
The great variety of meanings for synchysis, which is the much more common structure, comes from a technical use in Latin poetry, where a line in the form adjectiveA-adjectiveB-verb-nounA-nounB (because case inflections have to match, it's clear which adjective has to go with which noun) is known as a golden line, which is a delicious device but does greatly deviate from standard word order.
Regardless, both are originally technical jargon from ancient Greek rhetoric.