This is the 766th most frequent Polish word.
sejmie
"Sejmie" is the locative case of "Sejm," meaning "in the Sejm," referring to the lower house of the Polish parliament.
'Sejmie' is used in the locative case to describe the venue of the event happening.
Spotkanie w sejmie trwało kilka godzin.
The meeting in the parliament lasted several hours.
The use of 'sejmie', again in the locative case, is for indicating a specific place related to the context of the sentence.
Czy byłeś kiedyś w sejmie?
Have you ever been to the parliament?
The noun 'sejmie', in the locative case, is used here to indicate the location where the action takes place.