Noun, する verb, and の adjective
けっこん
「シャーク、私がフグと結婚したってどうして分かったの？」 「ただ人づてに聞いただけさ。」
"Shark, how did you know that I got married to Fugu?" "You know. I just heard it through the grapevine."
Let's bind this marriage up with a marriage. No better way to make a marriage happen than a marriage, right?
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.