Backbone
Noun
きがい
その教師は、教室で見て見ぬふりをされている問題に取り組む気概がなかった。
The teacher didn’t have the guts to deal with the problems in the classroom.
A spirit of approximation is the approximation of spirit. My approximation of your spirit? I think you have a strong spirit. I think you have backbone.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.