Two very fun words, with two very different meanings, despite their similarity.
A sentence that does this sort of grammatical wizardry:
“Our defeats are but stepping-stones to victory, and his victories are but stepping-stones to ruin.”
“The art of progress is to preserve order amid change and to preserve change amid order.”
-Alfred North Whitehead
The point at which a pair of chromatids “cross over” or touch to create genetic variation.
So, I leave you with this broken quote that makes almost no sense:
You can write a chiasmus about a chiasma, but you can’t describe a chiasmus with a chiasma.