fundamentally

to alter something in a very deep and important way

to cause a basic and significant change in something

to change the character or appearance of something completely

to be different in a basic or essential way

to have a profound and basic difference of opinion

different in the most basic and important aspects

important at the most basic and essential level

new in a way that changes the basic nature of something

having a very basic and serious mistake or weakness

solid and reliable in its basic principles or structure

clearly separate and different in the most basic ways

incorrect or mistaken at the most basic level

remaining the same in its most basic and important aspects

accurate and true in its most basic aspects

completely wrong in one's understanding or judgment

based on a completely wrong understanding of a situation