Flat
1. Lacking any complex internal structure.
"That bitty box has only a flat file system, not a hierarchical one."
The verb form is flatten.
Usually used pejoratively (at least with respect to file systems).
2. Said of a memory architecture like that of the VAX or Motorola 680x0 that is one big linear address space (typically with each possible value of a processor register corresponding to a unique address).
This is a Good Thing. The opposite is a "segmented" architecture like that of the Intel 80x86 in which addresses are composed from a base-register/offset pair.
Segmented designs are generally considered cretinous.
3. A flat domain is one where all elements except bottom are incomparable (equally well defined).
E.g. the integers.
[Jargon File]
