flat adj.
1. [common] Lacking any complex internal structure. "That
bitty box has only a flat
filesystem, not a hierarchical one." The verb form is flatten. 2. Said of a memory architecture
(like that of the VAX or 680x0) that is one big linear address
space (typically with each possible value of a processor register
corresponding to a unique core address), as opposed to a
`segmented' architecture (like that of the 80x86) in which
addresses are composed from a base-register/offset pair
(segmented designs are generally considered cretinous).
Note that sense 1 (at least with respect to filesystems) is
usually used pejoratively, while sense 2 is a Good Thing.