He raised his eyebrow in surprise, but said nothing.
This entry is concerned with the word бровь "eyebrow," denoting the fringe of hair growing over the ridge that forms the upper part of the orbit of the eye. This word refers only to humans. The term for "eyebrow" in the sense of "the ridge
that forms the upper part of the orbit of the eye" is надбровная дуга, though the word бровь is used in that sense in the expression рассечь бровь "make a cut in someone's eyebrow."