A deceptive outward appearance
To prevent (something) from being known
To change or modify so as to prevent recognition of the true identity or character of
His face was a mask of fright.
And yet, didn't clinical words like selective reduction and gestational carrier mask the facts?
He dropped the mask on the ground.
Brady pulled off his mask, trotting towards her.
The stocky man was hooded, wore a mask and was already in the room!