For words that need to be consistently pronounced in a special way, like a name or a scientific term, follow these steps.
Navigate to your email on the bottom left on the Home page. Click on it and you'll see the option Pronunciations (right below My profile).
Write how the word is spelt in the Word field, and how it's pronounced in the Pronunciation field.
Check Case sensitive if you would like to configure the custom pronunciation for this specified spelling only, and not its capitalized or lower-cased variation.
Then select the language this pronunciation applies to.
Confirm by clicking on Add. You can also listen to an audio preview of this pronunciation.
Note that Custom pronunciations don't support Convo Mode yet, but we are working on this.