Noun and する verb
あっぱく
圧迫に耐えないので、宇宙飛行士になる夢を諦めた。
I gave up my dream to become an astronaut because I couldn’t stand the pressure.
The pressure is urging outward. It's the pressure, so much pressure!
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. The あつ turns into a small っ, and はく goes to ぱく.