This is the 17857th most frequent Polish word.
łabędziej
"Łabędziej" means "swan's" or "of a swan" in English.
The word 'łabędziej' is an adjective derived from 'łabędź', meaning 'swan', and it modifies 'tafli', indicating that the lake's surface resembles or pertains to a swan.
Podziwiałem piękno łabędziej tafli jeziora.
I marveled at the beauty of the swan-like surface of the lake.
Here, 'łabędziej' describes 'damą', creating a metaphorical connection to the swan, suggesting grace or elegance.
W legendzie rycerz pokłonił się przed łabędziej damą.
In the legend, the knight bowed before the swan-like lady.
In this instance, 'łabędziej' modifies 'urodą', pointing to the aesthetic qualities associated with a swan.