This is the 71st most frequent Afrikaans word.
der
"Der" is an archaic or poetic form of "there" in Afrikaans.
Here, 'deur' is used as a preposition indicating through or passing within.
Die rivier vloei deur die dorp.
The river flows through the town.
In this sentence, 'deur' emphasizes the action of perusing or reading intermittently.
Ek het deur die boek geblaai.
I browsed through the book.
'Deur' in this context again serves as a preposition highlighting the path or passage taken.