The definition of hara-kiri is a method of suicide by falling on a sword.
An example of hara-kiri is a Japanese military man killing himself by falling stomach forward into his own sword to avoid execution.
Ritual suicide by cutting the abdomen: it is called seppuku by the Japanese, and was practiced by high-ranking Japanese of the military class in lieu of execution or to avoid disgrace.
Origin of hara-kiri
From Japanese 腹切り (はらきり (harakiri)). From 腹 (“belly”) (はら (hara)) + 切る (“cut”) (きる (kiru)).