Amazon Lex is a service for building conversational interfaces into any application using voice and text. Starting today, you can give Amazon Lex additional information about how to process speech input by creating a custom vocabulary. A custom vocabulary is a list of domain-specific terms or unique words (e.g., brand names, product names) that are more difficult to recognize. You create the list and add it to the bot definition, so Amazon Lex can use these words when determining the user’s intent or collecting information in a conversation. This allows you to enhance speech recognition and deliver an improved end-user experience.
Source:: Amazon AWS