Marriage Ceremony
Wedding
noun
If 結婚 is marriage, then a marriage ceremony is a marriage ceremony or wedding.
けっこんしき
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
「もう明日だけど、でも、やっぱり、私たちの結婚式を中止するべきだと思うの。」「僕もそれを言おうと思っていたんだ。」
"It’s tomorrow, but I think we should still cancel our wedding." "You took the words right out of my mouth."