ServiceDesk uses a 3rd party spell checker: https://www.karamasoft.com/ultimatespell/features.aspx
One can reference multiple dictionaries with the following steps:
1) Download the updated Dictionaries from: https://www.karamasoft.com/ultimatespell/dictionary.aspx NOTE: Not required, but recommended. 2) Open the respective .zip files and extract the .dic file. 3) Concatenate the respective .dic files. This can be done with Powershell. NOTE: It takes a while. type *.dic | Sort-Object -unique | Out-File concatenated.dic 4) Copy the 'concatenated.dic' file to: \Program Files\Symantec\Workflow\Shared\scripts\UltimateSpell\Dictionary\en-US\en-US.dic
Now, any part of ServiceDesk that uses Ultimate Spell will reference multiple dictionaries.