'Secret' in the Bible

But he himself turned back at the sculptured stones near Gilgal, and said, "I have a secret message for you, O king." And he commanded, "Silence." And all his attendants went out from his presence.

Now she had men lying in wait in an inner chamber. And she said to him, "The Philistines are upon you, Samson!" But he snapped the bowstrings, as a string of tow snaps when it touches the fire. So the secret of his strength was not known.