This is the 16154th most frequent Polish word.
ukochanej
"Ukochanej" means "beloved" or "darling" (feminine form) in English.
In this sentence, 'ukochanej' is an adjective in the dative case referring to someone who is cherished or loved.
Kupiłem różę dla mojej ukochanej.
I bought a rose for my beloved.
Here, 'ukochanej' is used as a noun (in the dative case) referring to a beloved person, typically a romantic partner.
Wiersz poświęcił swojej ukochanej.
He dedicated the poem to his beloved.
In this case, 'ukochanej' is an adjective in the locative case modifying the noun 'Warszawie', expressing affectionate endearment toward the city.