This is the 232nd most frequent Czech word.
republiky
"Republiky" in English means "of the republic" or "republics" (depending on context).
republika is used in its nominative singular form to denote a specific country.
Česká republika má nádhernou krajinu.
The Czech Republic has beautiful landscapes.
republik is used in its genitive plural form to denote possession or characteristics of multiple republican states.
Na výletě jsme projeli hranice několika republik.
On the trip, we crossed the borders of several republics.
republiky is used in its genitive singular form to denote ownership or association with the republic.