"gangrene caused by anemia due to continued pressure," 1833, from bed (n.) + sore (n.). A kind of ulcer liable to afflict persons long confined in bed and unable to change position.
Entries linking to bed-sore
bed n.
Old English bedd "bed, couch, resting place; garden plot," from Proto-Germanic *badja- (source also of Old Frisian, Old Saxon bed, Middle Dutch bedde, Old Norse beðr, Old High German betti, German Bett, Gothic badi "bed"). This is said to mean perhaps "sleeping place dug in the ground," if it is from PIE root *bhedh- "to dig, pierce" (source also of Hittite beda- "to pierce, prick," Greek bothyros "pit," Latin fossa "ditch," Lithuanian bedu, besti "to dig," Breton bez "grave"). But Boutkan doubts this and finds little reason to assume that Germanic peoples "(still) lived under such primitive circumstances that they dug out their places to sleep."
Both the sleeping and gardening senses are found in Old English; the specific application to planting also is found also in Middle High German and is the only sense of Danish bed. The meaning "bottom of a lake, sea, or watercourse" is from 1580s. The geological sense of "a thick layer, stratum" is from 1680s.
Bed and board "in bed and at the table" (early 13c.) was a term in old law applied to conjugal duties of man and wife; it also could mean "meals and lodging, room and board" (mid-15c.). Bed-and-breakfast in reference to overnight accommodations is from 1838; as a noun, in reference to a place offering such, by 1967.
sore n.
Middle English sore, from Old English sar "bodily pain or injury, wound; sickness, disease; state of pain or suffering," from root of sore (adj.). Now restricted to ulcers, boils, blisters, places where the skin is painfully raw (a sense in late Old English). In Old and Middle English also of mental pain. Compare Old Saxon ser "pain, wound," Middle Dutch seer, Dutch zeer, Old High German ser, Old Norse sar, Gothic sair.