Beneath the endless sky, students had to listen to the principal’s endless and boring speech.
I retreat! I yield! I can't take it anymore, it's so boring. Just imagine yourself giving up on whatever you're doing because you're so darn bored. You can't stand it. You have to retreat. You are ready to yield. Booooooring.
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.