to shake; to waver; to tremble
スキャンダルで彼の権威が揺るいだ。
His authority wavered due to the scandal.
王者の地位が揺るぎ、挑戦者が勢いを増した。
The champion's position shook, and the challenger gained momentum.
親の子への愛は決して揺るがない。
A parent's love for their child will never waver.