soil

Soil comes from Middle English soile, itself partly from Anglo-Norman soyl ("bottom, ground"), which traced to Latin solium ("seat, throne") — but that word got confused with the unrelated Latin solum ("ground, sole of the foot"). A separate strand came from Old English sol ("mud, mire, wet sand"), from a Proto-Germanic root meaning "thick liquid." A second, related verb sense — to soil, meaning to dirty something — came through Old French soillier and Old English solian, both also tracing back to that same "thick liquid" root.

What began as two separate threads — one meaning "ground" (tangled up by a Latin mix-up), the other meaning "mud" or "mire" — ended up fused into a single English word covering both the earth beneath our feet and the act of getting something dirty.

Soil is cognate with sully, which comes from the same Old French and Germanic roots meaning to make dirty.