DDT
     n : an insecticide that is also toxic to animals and humans;
         banned in the United States since 1972 [syn: {dichlorodiphenyltrichloroethane}]
Source: WordNet® 2.0

DDT /D-D-T/ n. [from the insecticide
   para-dichloro-diphenyl-trichloroethene] 1. Generic term for a program
   that assists in debugging other programs by showing individual machine
   instructions in a readable symbolic form and letting the user change
   them. In this sense the term DDT is now archaic, having been widely
   displaced by `debugger' or names of individual programs like `adb',
   `sdb', `dbx', or `gdb'. 2. [ITS] Under MIT's fabled {{ITS}} operating
   system, DDT (running under the alias HACTRN, a six-letterism for `Hack
   Translator') was also used as the {shell} or top level command language
   used to execute other programs. 3. Any one of several specific DDTs
   (sense 1) supported on early {DEC} hardware and CP/M. The PDP-10
   Reference Handbook (1969) contained a footnote on the first page of the
   documentation for DDT that illuminates the origin of the term:

  Historical footnote: DDT was developed at MIT for the PDP-1
  computer in 1961.  At that time DDT stood for "DEC Debugging
  Tape".  Since then, the idea of an on-line debugging program has
  propagated throughout the computer industry.  DDT programs are now
  available for all DEC computers.  Since media other than tape are
  now frequently used, the more descriptive name "Dynamic Debugging
  Technique" has been adopted, retaining the DDT abbreviation.
  Confusion between DDT-10 and another well known pesticide,
  dichloro-diphenyl-trichloroethane (C14-H9-Cl5) should be minimal
  since each attacks a different, and apparently mutually exclusive,
  class of bugs.
  
   (The `tape' referred to was, incidentally, not magnetic but paper.)
   Sadly, this quotation was removed from later editions of the handbook
   after the {suit}s took over and {DEC} became much more `businesslike'.

   The history above is known to many old-time hackers. But there's more:
   Peter Samson, compiler of the original {TMRC} lexicon, reports that he
   named `DDT' after a similar tool on the TX-0 computer, the direct
   ancestor of the PDP-1 built at MIT's Lincoln Lab in 1957. The debugger
   on that ground-breaking machine (the first transistorized computer)
   rejoiced in the name FLIT (FLexowriter Interrogation Tape).


Source: The Jargon File

DDT
     Dynamic Debugging Tool (DEC)
     
     
Source: Virtual Entity of Relevant Acronyms