Firm/strong defense: protecting well against attacks or challenges; in sports often refers to solid defensive play.
チームは堅守で相手の攻撃を封じた。
The team neutralized the opponent's attack with solid defense.
彼は守備を堅守することで試合の流れを変えた。
By holding firm on defense, he changed the course of the game.
経営は堅守を重視してリスクを回避した。
Management emphasized a conservative defense to avoid risks.