This is a jukugo word that uses the on'yomi readings of the kanji. You didn't learn this reading for 和 yet, so here's a mnemonic to help you:
The only thing you ever hear the Buddhist High Priest say is "Oooooo" (お). It must be some kind of Buddhist humming or chanting. Every time you think about him you hear that o sound in your head.
Once upon a time there was a high priest who loved starch syrup.