File generated by Addict, a tool used to add spell checking capabilities to applications; contains a user dictionary for the target program; used by various applications for both spell checking and thesaurus capabilities.

If there are multiple user accounts on a computer, there may be multiple ADU user dictionary files, one per user. Additionally, sometimes programs have a default spell check ADU file called autocorrect.adu, which is used for correcting the word spelling as the user types. NOTE: The Addict add-on supports Delphi, C++ Builder, Turbo Delphi, and Turbo C++ development environments.