unnoticed

He took up a second letter which had lain unnoticed upon the table whilst he had been absorbed with the first.

The Count of Morcerf was not a person to excite either interest or curiosity in a place of public amusement; his presence, therefore, was wholly unnoticed, save by the occupants of the box in which he had just seated himself.

Madame Danglars seldom allowed remarks of this kind to pass unnoticed, but, to the surprise of the young people, she pretended not to hear it, and said nothing.