wonder vs happening

wonder and happening both are nouns.

Word	Noun	Adjective	Verb	Adverb
wonder	Yes	No	Yes	No
happening	Yes	No	No	No

As nouns, happening is a hypernym of wonder; that is, happening is a word with a broader meaning than wonder:

Other hypernyms of wonder include natural event, occurrence, occurrent.

wonder (noun)	happening (noun)
a state in which you want to learn more about something	an event that happens
something that causes feelings of wonder
the feeling aroused by something strange and surprising

wonder (verb)	happening (verb)
have a wish or desire to know something
place in doubt or express doubtful speculation
be amazed at