The monkeys’ calls warn other animals of approachers.
1589, Paul Ive (translator), Instructions for the Warres by Raimond Beccarie de Pavie, Seigneur de Fourquevaux, London: Thomas Man and Toby Cooke, Chapter 5, p. 38,
[…] houses or other thing standing néere vnto a towne, or fort, are meanes to surprise and approach vnto it, and the approacher not be discouered, or impeached by the defenders.
(astronomy) An asteroid on a near-Earth trajectory.