Resolution, Conviction
Noun and する verb
けっしん
あなたのおかげで、せい形手じゅつをする決心がつきました。
Thanks to you, I’ve decided to get plastic surgery.
インスタセレブになるというトーフグの決心はトウフと同じぐらいかたい。
Tofugu's resolution to being an Instagram celebrity is as firm as Tofu.
ついに、あなたに、どこから私の誕生日プレゼントの酒を買ってきてもらうか決心したよ。それは…日本だ。楽しんできてね！
I’ve finally made up my mind about where you’ll be buying me drinks for my birthday... In Japan. Enjoy!
When you decide with your heart you have true determination, unlike when you decide with your mind.
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. Just make sure you take note of the shortened つ. So, けつ goes to けっ.