He could not carry it unnoticed in his belt or under his arm.
Her phobia didn't go unnoticed by Alex.
She leaped from her bed, the book falling to the floor unnoticed.
Then he could slip out unnoticed.
The two books mentioned remained unnoticed by the reading public, and Lotze first became known to a larger circle through a series of works which aimed at establishing in the study of the physical and mental phenomena of the human organism in its normal and diseased states the same general principles which had been adopted in the investigation of inorganic phenomena.