This is the 13397th most frequent German word.
beigetreten
"Beigetreten" means "joined" or "became a member of."
In this sentence, 'beigetreten' is the past participle of the verb 'beitreten', used in the present perfect tense to describe the act of joining an organization.
Ich bin dem Verein gestern beigetreten.
I joined the club yesterday.
Here, 'beigetreten' indicates that the subject has joined a discussion or communication exchange, expressing his involvement.
Er hat der Diskussion beigetreten, um seine Meinung zu äußern.
He joined the discussion to express his opinion.
This usage illustrates 'beigetreten' within a dependent clause describing an action completed prior to another event, showing the narrative timeline.