Entries linking to crumby
Middle English crome, crumme, from Old English cruma "fragment of bread or other food, a morsel, small fragment," from a West Germanic root of obscure origin (compare Middle Dutch crume, Dutch kruim, German Krume); perhaps from a PIE word for "small particle of bread" and cognate with Greek grumea "bag or chest for old clothes" (Beekes writes: "In origin, the word probably denoted small things of little value, later also the chest, etc.), Albanian grime.
The unetymological -b- appeared mid-15c., in part by analogy with words like dumb. Slang meaning "lousy person" is 1918, from crumb, U.S. slang for "body-louse" (1863), which were so called from resemblance.
1560s, "easily crumbled;" 1570s, "like bread," from crumb + -y (2). Slang meaning "shoddy, filthy, inferior, poorly made" was in use by 1859, probably from the first sense, but influenced by crumb in its slang sense of "louse." The "like bread" sense probably accounts for 18c. (and later in dialects) use, of a woman, "attractively plump, full-figured, buxom." Related: Crummily; crumminess.