The FIFO input-character buffer in an EIA-232 serial 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.

Nearby terms:

Silicon Graphics, Inc.Siliwoodsilly walksiloSilver Booksilver bulletSIM

Try this search on Wikipedia, Wiktionary, Google, OneLook.