[Latin solum, soil.]
This ending forms specialist names for soil types. Examples are vertisol (from vertical), a clayey soil that forms deep vertical cracks on drying; palaeosol (US paleosol), a stratum or soil horizon which was formed as a soil in a past geological age (Greek palaios, ancient); and mollisol, a soil of temperate grassland with a dark, humus-rich surface layer (Latin mollis, soft). One common term of this type, podzol, an infertile acidic soil with an ash-like leached subsurface layer, actually derives from Russian (pod, under, plus zola ashes), but is often spelled podsol to match the others.
Other words ending in -sol come from several sources: in aerosol, cytosol, hydrosol, and plastisol the ending is the word sol (from the first element of solution), indicating a fluid suspension of a colloidal solid in a liquid; in cortisol and creosol it is really -ol, but happens to be preceded by s; in parasol the last element is Latin sol, sun.