:swap space: n. Storage space, especially temporary storage space
used during a move or reconfiguration. "I'm just using that corner
of the machine room for swap space."
-- The AI Hackers Dictionary
ilo: n. The FIFO input-character buffer in an RS-232 line card. So
called from DEC terminology used on DH and DZ line cards for the
VAX and PDP-11, presumably because it was a storage space for
fungible stuff that went in at the top and came out at the bottom....