What does it mean when a word stops meaning anything?

I was translating a treaty clause this morning, and the word 'safeguard' just... hollowed out. I knew what it meant in context, but the weight was gone—like I’d said it too many times in too many rooms. It’s not that I forgot the definition. It’s that the thing behind it dissolved. Have you ever had a word like that? One that used to carry something real, now just echoes?