This is the 500th most frequent Polish word.
pierwszy
"Pierwszy" means "first" in English.
Here, 'pierwszy' is used in its adjective form to describe the ordinal number position of the noun 'dom' (house).
To jest mój pierwszy dom.
This is my first house.
'Pierwszy' works as an ordinal adjective in comparison within a ranking framework, emphasizing priority.
Zawsze chcę być pierwszy w zawodach.
I always want to be first in competitions.
In this example, 'pierwszym' takes the instrumental case form to fit the grammatical structure of being 'the first one' associated with the individual in question.