Unshakeable

I was assailed by the stupid, but unshakeable, idea that if I was imprudent enough to move my hand I'd be noticed.

Our conviction is unshakeable.

We are unshakeable.

That's an unshakeable truth.

Their trust in each other is unshakeable.

Parents of gifted children hold an unshakeable belief in heredity.

Nothing could disturb our unshakeable friendship.