This is the 2108th most frequent Russian word.
рийгикогу
The Russian word "Рийгикогу" refers to the "Riigikogu," which is the Parliament of Estonia.
Here, "рийгикогу" is used as the subject of the sentence, naming Estonia's legislative body.
Рийгикогу является парламентом Эстонии.
The Riigikogu is the parliament of Estonia.
In this sentence, "рийгикогу" is used to specify the organization responsible for legislative discussions.
На следующей неделе Рийгикогу обсудит новый закон.
Next week, the Riigikogu will discuss a new law.
This usage integrates "рийгикогу" to refer to the collective body of its members.