DDT

DDT
—n
	dichlorodiphenyltrichloroethane; a colourless odourless substance used as an insecticide. It is toxic to animals and is known to accumulate in the tissues. It is now banned in the UK

DDT (dē'dē-tē')
n.
Dichlorodiphenyltrichloroethane; a colorless contact insecticide, toxic to humans and animals when swallowed or absorbed through the skin, that has been banned in the United States for most uses since 1972.

DDT   (dē'dē-tē')  Pronunciation Key  Short for dichlorodiphenyltrichloroethane. A powerful insecticide that is also poisonous to humans and animals. It remains active in the environment for many years and has been banned in the United States for most uses since 1972 but is still in use in some countries in which malaria is endemic. Chemical formula: C14H9Cl5.

DDT definition

A colorless insecticide that kills on contact. It is poisonous to humans and animals when swallowed or absorbed through the skin. DDT is an abbreviation for dichlorodiphenyltrichloroethane.

Note: Although DDT, when it was first invented, was considered a great advance in protecting crops from insect damage and in combating diseases spread by insects (such as malaria), discoveries led to its ban in many countries. Residue from DDT has been shown to remain in the ecosystem and the food chain long after its original use, causing harm and even death to animals considered harmless or useful to man.

DDT definition

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. Under MIT's fabled ITS operating system, DDT (running under the alias HACTRN) was also used as the shell or top level command language used to execute other programs.
3. Any one of several specific debuggers supported on early DEC hardware. The DEC 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 suits 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 transistorised computer) rejoiced in the name FLIT (FLexowriter Interrogation Tape).
[Jargon File]

DDT dichlorodiphenyltrichloroethane