David Foster Wallace, The Pale King, 2011, page 73“Our mutual contract here is based on the presumptions of (a) my veracity, and (b) your understanding that any features or semions that might appear to undercut that veracity are in fact protective legal devices, not unlike the boilerplate that accompanies sweepstakes and civil contracts, and thus are not meant to be decoded or ‘read’ so much as merely acquiesced to as part of the cost of our doing business together, so to speak, in today’s commercial climate.
A semion is technically part of an anyon, the latter of which is defined in the OED as "a particle having characteristics intermediate between those of fermions and bosons in two-dimensional space." However, it seems Wallace uses the word as a form closer to "semiotics." A later search reveals that semion is Greek for "sign."
From the Infinite Jest wiki: