areole (noun, pl. areoles, variant spelling: sl. areola, pl. areolae) – a small, usually rounded to polygonal or irregular area, appearing like an island or a tile in a mosaic; (1) a small, flattened part of a lichen thallus separated from the rest of the thallus by deep, narrow to wide cracks or more or less scattered on the substrate ... with an areolate growth from); (2) small, discrete corticated patches on the thallus surface ... with an areolate surface). Related terms: pruina. This is:part of thallus surface.