This is the 4330th most frequent German word.
fiesen
"Fiesen" is not a standard German word; it may be a misspelling or regional slang. It could derive from "fies," meaning "mean" or "nasty."
Used as an adjective meaning unpleasant, mean, or malicious.
Der fiese Nachbar beschwerte sich jeden Morgen über den Lärm.
The mean neighbor complained every morning about the noise.
Used as an adjective describing something unlikable or undesirable.
Was musste ich für diese fiese Aufgabe tun?
What did I have to do for this nasty task?
Used as an adjective to describe something unpleasant or shocking.