This is the 1789th most frequent Swedish word.
festen
"The party" or "the celebration."
Here, 'festen' is used as the noun 'party' in the definite form, denoting a specific event known to the speakers.
Festen var mycket livlig och underhållande.
The party was very lively and entertaining.
In this sentence, 'festen' again appears as a definite noun, referring to a particular party the context or prior conversation has identified.
Vi gick alla till festen vid sjön.
We all went to the party by the lake.
This usage of 'festen' depicts a specific party, highlighted through additional descriptive context ('big').