This is the 9682nd most frequent Polish word.
zadnim
"Zadnim" means "rear" or "last" in English, as a form of the adjective "zadni," referring to position or sequence.
The term 'zadnim' functions as an adjective specifying the location as 'rear' or 'back', describing 'siedzeniu' (seat).
Siedziałem na zadnim siedzeniu samochodu.
I was sitting in the rear seat of the car.
Here, 'zadni' acts as an adjective describing the noun 'ogród' (garden) as located at the back or rear.
Z tyłu domu znajdował się zadni ogród.
Behind the house, there was a rear garden.
In this sentence, 'zadnią' modifies 'częścią' (part) as associated with the rear area of the building.