Glaucous (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (Larus hyperboreus), glaucous-winged gull (Larus glaucescens), glaucous macaw (Anodorhynchus glaucus), and glaucous tanager (Thraupis glaucocolpa).

The term