What is .UD file extension?
User dictionary created for OmniPage, an optical character recognition (OCR) program; contains custom words, such as proper nouns, technical terms, and abbreviations that have been added by the user; supplements the program's built-in dictionary, which assists in the text recognition process.
NOTE: OmniPage includes multiple dictionaries for different languages. Each of these dictionaries may have its own user dictionary. Therefore, several user dictionaries may exist at one time.
You can see a list of software programs here on easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.