1. Expressions (phrases, clauses, etc.), Godan verb with 'su' ending

   to finish off; to ensure (something) is dead; to deliver the coup de grace

   ライオンが獲物に一撃でとどめを刺した。

2. to put an end to; to deliver the final blow

3. to be the best for A

   as ＡはＢに止めを刺す

Also written 止めを刺す【とどめをさす】todomewosasu