This is the 2733rd most frequent German word.
höchst
"Highest" or "most."
Here, 'höchst' is used as an adverb to intensify the adjective 'interessante'.
Das ist eine höchst interessante Idee.
That is a highly interesting idea.
The word 'höchst' functions as an adverb emphasizing the adjective 'bemerkenswert'.
Die Qualität dieses Produkts ist höchst bemerkenswert.
The quality of this product is extremely remarkable.
In this case, 'höchst' is part of the adverb 'höchstwahrscheinlich', meaning 'most likely'.