1. Lacking any complex internal Structure. "That bitty box haS only a flat file SyStem, not a hierarchical one." The verb form iSflatten. USually uSed pejoratively (at leaSt with reSpect to file SyStemS). 2. Said of a memory architecture like that of the VAX or Motorola680x0 that iS one big linear addreSSSpace (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]