This is the 3350th most frequent Swedish word.
anonymt
"Anonymt" means "anonymously" in English.
In this sentence, 'anonymt' is used as an adjective to describe the noun 'brev', meaning the letter was written without disclosing the sender's identity.
Jag skrev ett anonymt brev till min vän.
I wrote an anonymous letter to my friend.
Here, 'anonymt' is functioning as an adverb describing the verb 'deltog', indicating that her participation did not reveal her identity.
Hon deltog anonymt i undersökningen.
She participated anonymously in the survey.
In this usage, 'anonymt' is an adverb modifying the verb phrase 'göra saker', emphasizing that the actions can be done without revealing one's identity.