Jack: slang for money
"With this town full of guys making good jack, that would treat you right" (Light in August, p. 192).
Jellybean: 1920s slang for a self-consciously fashionable adolescent male
"Are you hiding out in the woods with one of those dam slick-headed jellybeans?" (The Sound and the Fury, p. 184).
Jest: as in "just"
"I jest thought…" (As I Lay Dying, p. 44).
Jimson weed: a poisonous plant with large trumpet-shaped flowers
"Here's you a jimson weed" (The Sound and the Fury, p. 6).
"…the stick jouncing on my shoulder" (As I Lay Dying, p. 54).
Juggernautish: variant of "juggernaut," something that elicits blind and destructive devotion
"… leaning a little stiffly forward as though in some juggernautish simulation of terrific speed…" (Light in August, p. 203).
Keer: as in "care"
Dewey Dell a-takin good keer of her…" (As I Lay Dying, p. 44).
Ketch: as in "catch"
"Cant nobody else ketch hit" (As I Lay Dying, p. 42).
"'Hold him! Hold him! Ketch him! Ketch him!" (Light in August, p. 324).
Kilt: as in "killed"
"He kilt her. He kilt her" (As I Lay Dying, p. 54).
Knobnot: a childish insult
"'You're a knobnot.' Caddy said. Jason cried" (The Sound and the Fury, p. 36).
Kyo: as in "cure"
"Mammy aint feelin well dis mawnin.
"…Rev'un Shegog'll kyo dat" (The Sound and the Fury, p. 292).
Laidby: a cultivated crop that will require no further attention until it is picked at harvest time
"…between the green rows of laidby cotton…" (As I Lay Dying, p. 3).
"Well, I have brought you back the devil's laidby crop" (Light in August, p. 377).
Lantun: as in "lantern"
"I reckon I had better clean dat lantun up" (The Sound and the Fury, p. 114).
Latch string: a string for raising the latch of a door by a person outside
"I'll make him think that dam red tie is the latch string to hell, if he thinks he can run the woods with my niece" (The Sound and the Fury, p. 241).
"He should be lawed for treating her so" (As I Lay Dying, p. 187).
Leastways: at least
"Leastways, we might as well go on and make like we did" (As I Lay Dying, p. 74).
Leda: a woman in Greek myth raped by Zeus, who came to her in the shape of a swan
"Leda lurking in the bushes, whimpering and moaning for the swan, see" (The Sound and the Fury, p. 167).
Lessen: as in "unless"
"Lessen you behave, we will leave you" (As I Lay Dying, p. 63).
Liberry: as in "library," a place in which literary materials are kept, including a room in a private home for such a collection
"Luster going to take him to the liberry and play with him till I get his supper done" (The Sound and the Fury, p. 60).
Lick: (1) a sudden hard stroke; (2) speed, pace
"One lick less" (As I Lay Dying, p. 15).
"She's hitting that lick like she's been at it for a right smart while…" (Light in August, p. 9).
Liefer: as in "like to"
"I'd liefer go back there" (As I Lay Dying, p. 200).
Lochinvar: "Young Lochinvar" is a character in a poem by Sir Walter Scott about a brave highlander who rides off with the lady he loves before she is forced to marry another man
"Young Lochinvar rode out of the west a little too soon, didn't he?" (The Sound and the Fury, p. 93).