This is the 2016th most frequent German word.
kostete
"Cost" or "costed" (past tense of "kosten," meaning to cost).
Here, 'kostete' is the simple past tense of 'kosten,' meaning 'to cost,' used to indicate the price of an item in the past.
Das Kleid kostete früher 50 Euro.
The dress used to cost 50 euros.
In this usage, 'kostete' is used metaphorically to describe the expense in terms of effort needed to solve a problem.
Es kostete mich viel Mühe, das Problem zu lösen.
It cost me a lot of effort to solve the problem.
Here, 'kostete' reflects a figurative cost, indicating loss or consequence caused by an event.