This is the 448th most frequent Dutch word.
waaronder
"Waaronder" means "including," "among which," or "under which" in English.
The word 'waaronder' is used here to introduce examples included within a broader category, specifically his hobbies.
Hij heeft veel hobby's, waaronder schilderen en koken.
He has many hobbies, including painting and cooking.
Here, 'waaronder' is used to specify particular instances within a set of causes for the delay.
Er zijn verschillende redenen, waaronder de slechte weersomstandigheden, voor de vertraging.
There are several reasons, including the bad weather conditions, for the delay.
In this sentence, 'waaronder' introduces individual items included in a subset of a larger group, specifically the guests.