sillion
The thick, voluminous, and shiny soil turned over by a plow.
rare, uncountable
No wonder of it: shéer plód makes plough down sillion / Shine, and blue-bleak embers, ah my dear, / Fall, gall themselves, and gash gold-vermillion.
Where it comes from
Revived by Gerard Manley Hopkins in his 1877 (published posthumously in 1918) poem The Windhover; ultimately related to French sillon (“furrow”).
Adapted from the Wiktionary entry sillion (CC BY-SA 4.0).