This is the 1261st most frequent Dutch word.
dik
"Thick" or "fat."
In this sentence, 'dik' (thick) is used to describe the thickness of the coat, a physical attribute.
Hij droeg een dikke jas in de winter.
He wore a thick coat in the winter.
Here, 'dik' (strong) is used metaphorically to signify the strength of the friendship.
Ze hebben een dikke vriendschap opgebouwd.
They have built a strong friendship.
In this case, 'dik' refers to the physical dimensions of the book, particularly its cover thickness due to the page count.