Selection.LanguageID (Word)

Returns or sets the language for the specified object. Here you can find possible values for WdLanguageID.

For a custom dictionary, you must first set the LanguageSpecific property to True before specifying the LanguageID property. Custom dictionaries that are language-specific check only text that is formatted for that language. Some of the constants listed above may not be available to you, depending on the language support (U.S. English, for example) that you have selected or installed.

Selection.LanguageID = wdAfrikaans