Why is the ninth month called September?
early 13c., "to defile or pollute with sin," from Old French soillier "to splatter with mud, to foul or make dirty," originally "to wallow" (12c., Modern French souillier), from souil "tub, wild boar's wallow, pigsty," which is from either Latin solium "tub for bathing; seat," or Latin suculus "little pig," from sus "pig." Literal meaning "to make dirty, begrime" is attested from c.1300 in English. Related: Soiled; soiling.
c.1300, originally "land, area, place," from Anglo-French soil "piece of ground, place" (13c.), from an merger or confusion of Old French sol "bottom, ground, soil" (12c., from Latin solum "soil, ground;" see sole (n.1)), Old French soeul, sueil "threshold, area, place" (from Latin solium "seat"), and Old French soil, soille "a miry place," from soillier (see soil (v.)).
Meaning "place of one's nativity" is from c.1400. Meaning "mould, earth, dirt" (especially that which plants grow in) is attested from mid-15c.
"filth, dirt, refuse matter, sewage, liquid likely to contain excrement," c.1600, earlier "miry or muddy place" (early 15c.), from Old French soille "miry place," from soillier (v.) "to make dirty," and in part a native formation from soil (v.). This is the sense in archaic night-soil.
The loose top layer of the Earth's surface, consisting of rock and mineral particles mixed with decayed organic matter (humus), and capable of retaining water, providing nutrients for plants, and supporting a wide range of biotic communities. Soil is formed by a combination of depositional, chemical, and biological processes and plays an important role in the carbon, nitrogen, and hydrologic cycles. Soil types vary widely from one region to another, depending on the type of bedrock they overlie and the climate in which they form. In wet and humid regions, for example, soils tend to be thicker than they do in dry regions. See more at A horizon, B horizon, C horizon., See illustration at ABC soil.