The American Heritage® Dictionary of the English Language, 4th Edition
n. The act of catching sight of something, especially something unusual or searched for: a sighting of a whale in the harbor; a reported sighting of a UFO.
n. The act of catching sight of something, especially something searched for
v. Present participle of sight.
the GNU version of the Collaborative International Dictionary of English
a. & n. from sight, v. t.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. the act of observing
Word Usage
"The _sighting notch_ in the slide with the rear sight leaf down, is the same height as is the sighting in the drift slide when the rear sight leaf is raised and set at 530 yards."