This is the 706th most frequent Estonian word.
riigi
The Estonian word "riigi" is the genitive form of "riik," meaning "of the state" or "of the country."
Here 'riigi' is the genitive form of the noun 'riik', denoting possession, indicating 'of the country'.
Riigi pealinn on Tallinn.
The capital of the country is Tallinn.
In this sentence, 'riigi' again reflects possession, specifying that the laws belong to the state.
Riigi seadused peavad olema õiged.
The laws of the state must be just.
Here 'riigi' is used adjectivally, describing the 'economic situation' as pertaining to the country.