Fighting Spirit
noun
You must struggle with intention. You know you're going to win this way. Show your fighting spirit.
とうし
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
その戦闘ロボットは、メラメラと闘志を燃やしていた。
The battle robot was full of fighting spirit.