Entries linking to brownfield
Old English brun "dark, dusky," developing a definite color sense only 13c., from Proto-Germanic *brunaz (source also of Old Norse brunn, Danish brun, Old Frisian and Old High German brun, Dutch bruin, German braun), from PIE root *bher- (2) "bright; brown."
The Old English word also had a sense of "brightness, shining," preserved only in burnish. The Germanic word was adopted into Romanic (Middle Latin brunus, Italian and Spanish bruno, French brun). Brown sugar is from 1704. Brown Bess, slang name for old British Army flintlock musket, is first recorded 1785. Brown study "state of mental abstraction or meditation" is from 1530s; OED says the notion is "gloomy." Brown-paper "kind of coarse, stout, unbleached paper used for wrapping" is from 1650s.
Old English feld "plain, pasture, open land, cultivated land" (as opposed to woodland), also "a parcel of land marked off and used for pasture or tillage," probably related to Old English folde "earth, land," from Proto-Germanic *felthan "flat land" (Cognates: Old Saxon and Old Frisian feld "field," Old Saxon folda "earth," Middle Dutch velt, Dutch veld Old High German felt, German Feld "field," but not found originally outside West Germanic; Swedish fält, Danish felt are borrowed from German; Finnish pelto "field" is believed to have been adapted from Proto-Germanic). This is from PIE *pel(e)-tu-, from root *pele- (2) "flat; to spread." The English spelling with -ie- probably is the work of Anglo-French scribes (compare brief, piece).
As "battle-ground," c. 1300. Meaning "sphere or range of any related things" is from mid-14c. Physics sense is from 1845. Collective use for "all engaged in a sport" (or, in horse-racing, all but the favorite) is 1742; play the field "avoid commitment" (1936) is from notion of gamblers betting on other horses than the favorite. Cricket and baseball sense of "ground on which the game is played" is from 1875. Sense of "tract of ground where something is obtained or extracted" is from 1859. As an adjective in Old English combinations, often with a sense of "rural, rustic" (feldcirice "country-church," feldlic "rural"). Of slaves, "assigned to work in the fields" (1817, in field-hand), opposed to house. A field-trial originally was of hunting dogs.