The headline of this post uses descent in two senses: This post discusses the etymological origin of hag, but it also points out how the connotation of the term has plummeted in status.
The contemporary connotation of hag is “old woman,” with additional senses of a careless, ugly, or evil appearance; the offensive term “fag hag” refers to a straight woman who associates with gay men. In the Middle Ages, the term referred to a female demon or an evil spirit, but it was originally associated with highly respected oracles, or soothsayers.
Hag is the truncated version of the Old English term hagetes (also spelled hagtesse), meaning “witch” or “sorceress.” The second syllable, later misidentified as a mere suffix, was lopped off, but that’s the essential element; it’s probably related to words in other languages referring to demons or spirits, while hag is likely cognate with hedge. The significance of that term is that hedges were considered the boundary between civilization and the wild, and witches—and reclusive women with mysterious healing abilities who were sometimes accused of being witches—straddled both worlds.
A term with a loose association, hagridden, refers to sleep paralysis, because of the belief that one’s sense of being immobilized while lying in bed was caused by a spirit bearing down on the sufferer; by extension, the term also means “tormented,” and the verb hagride means “torment.” Similarly, the rare adjective hagged originally meant “bewitched” and later acquired the sense of “gaunt,” due to the belief that such an appearance was the result of bewitchment.
Haggard, originally meaning “unruly” or “wild,” is not directly related—it comes from the Old French phrase faulcon hagard (“wild falcon”)—but it’s a distant relation that acquired the sense of “worn” by association with hag.
Other related words include the archaic noun haw, meaning “enclosure” (the first syllable of hawthorn), and hex, which originally referred to a witch but later came to apply to a witch’s spell. (Haggle has a separate derivation; it’s related to hack.)