This is the 8475th most frequent German word.
kieler
"Kieler" refers to something or someone from Kiel, a city in northern Germany.
Here 'Kieler' is used as an adjective to describe the type of event, relating to the city Kiel.
Kieler Woche zieht jedes Jahr viele Besucher an.
Kieler Woche attracts many visitors every year.
In this sentence, 'Kieler' qualifies 'Old Town,' indicating its location or association with Kiel, acting as an attributive adjective.
Die Kieler Altstadt ist reich an Geschichte.
The Kiel Old Town is rich in history.
The word 'Kieler' here is used as a noun to denote a person who is native to or resides in Kiel.