You can add additional dictionary files to LiveCycle Designer ES to suit your needs. That is, if you want to expand the list of correctly spelled words that LiveCycle Designer ES refers to when spell checking a form, you can add one or more custom dictionary files (*.clam) for a specific language or for all supported languages. For example, you can add a custom dictionary of unique terms for specialized industries such as medicine, law, engineering, insurance, or finance. Keep in mind that if you want to add the words in a custom dictionary file to a particular language instead of all languages, you must include the correct language extension in the custom dictionary file name. Let’s say you want to add a custom dictionary file to French Canadian only, you must add fr_CA to the file name like this, [file name]-fr_CA.clam. If you do not include a language extension in the file name, the words in the file will be considered correct for all languages.
Note:
You can also add more standard dictionary files (*.lex) for languages that LiveCycle Designer ES does not already support, by manually adding the files to the folder located at \Program Files\Common Files\Adobe\Linguistics\Providers\Proximity.
You can use the options in the Spelling panel of the Options dialog box to add dictionaries and select which dictionaries are used when performing spell-check operations.
3.
Browse to the dictionary file you want to add to LiveCycle Designer ES and click Open. The dictionary is added to the list of installed dictionaries.
See also 

To add a dictionary