This is the 56th most frequent Polish word.
czy
"czy" = "whether" or a question particle.
'Czy' is used as a particle to introduce a yes/no question in Polish.
Czy idziesz jutro do kina?
Are you going to the cinema tomorrow?
'Czy' is used to signify 'or', presenting an alternative between two choices in a question.
Czy to jabłko jest dojrzałe, czy zielone jeszcze?
Is this apple ripe or still green?
'Czy' is used as a conjunction introducing a dependent clause signifying uncertainty.