IPA: //fʌnˈdæmənˌtɛli//
KK: /fʌnˈdæmənˌtɛli/
In a basic or essential way; at the most important level.
The two theories are fundamentally different from each other.
Fundamentally → It is formed from "fundamentum" (from Latin, meaning foundation) and the suffix "-ally" (meaning in a manner relating to). The word "fundamentally" means in a manner that relates to the foundation or basic principles of something.
Think of the word 'foundation' when you hear 'fundamentally' — it helps you remember that it refers to the basic principles or underlying aspects of something.