clandestine, secret or furtive
The backstairs (stairs at the rear of a building).
Being or kept hidden.
Private seclusion.
A piece of knowledge that is hidden and intended to be kept hidden.
The key or principle by which something is made clear; the knack.
A form of steel skullcap.
Something not understood or known.
Any prayer spoken inaudibly and not aloud; especially, one of the prayers in the Tridentine Mass, immediately following the "orate, fratres", said inaudibly by the celebrant.
To make or keep secret.
To hide secretly.