*Some of these glossary definitions have been adapted and reproduced by permission of The American Heritage Dictionary of the English Language, Fourth Edition. Copyright © 2002 by Houghton Mifflin Company. Many computer and Web-related definitions have been contributed by Jason Snart, College of DuPage.

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database A collection of data arranged for ease and speed of search and retrieval.

deductive argument An argument form in which one reasons from premises that are known or assumed to be true to a conclusion that follows necessarily from these premises.

deep Web Information stored on databases which are not directly available to search engines.

define To describe the nature or basic qualities of; explain. OR To specify distinctly.

desirability The degree to which something is worth having, seeking, doing or achieving, as by being useful, advantageous, or pleasing.

dialect A regional or social variety of a language distinguished by pronunciation, grammar, or vocabulary, especially a variety of speech differing from the standard literary language or speech pattern of the culture in which it exists.

dialogue A systematic exchange of ideas or opinions.

dilemma A situation that requires a choice between options that are or seem equally unfavorable or mutually exclusive.

disadvantage An unfavorable condition or circumstance.

disjunctive Serving to separate or divide; in logic, presenting alternative terms with the assertion that only one is true.

disprove To prove to be false, invalid, or in error; refute.

distinguish To perceive as being different or distinct.