@takanori uoi The word list cannot be listed through an API since this is defined at the base models of the speech service and MS reserves the right to mask or remove any word that is deemed inappropriate. Such words will not be returned by the Speech service, whether or not you enabled profanity filtering.
Also, you cannot define a list for inappropriate words that can be customized through speech service.
A new preview service Azure AI content safety has this capability if you need to create a custom list and use it in your application. At this moment this is an independent service that is still in preview. I hope this helps!!
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