fundamentally
adv.at the most basic or important level. You use this to talk about the core truth of something, even if it looks different on the outside.
adv.relating to the most basic or essential parts of something; in a way that affects the core nature of a person, thing, or idea.
“The two plans are fundamentally the same.”
“While the new software looks different, the way it processes data remains fundamentally unchanged.”
“The philosopher argued that despite cultural differences, all human societies are fundamentally driven by the same basic needs for security and social connection.”
Typically placed before the adjective or verb it modifies to emphasize a core characteristic.
Usage fundamentally different · fundamentally important
“Perhaps the biggest lesson from our year-long investigation was this: people still fundamentally care about their High Streets.”
“Artificial intelligence has been used to develop a "fundamentally new" type of vaccine that could protect against large swathes of viruses and prevent pandemics, say researchers.”
Common in science writing
From fundamental + -ly.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.