Words related to bacillus
1847, plural of Modern Latin bacterium, from Greek bakterion "small staff," diminutive of baktron "stick, rod, staff, cudgel." So called because the first ones observed were rod-shaped. Introduced as a scientific word 1838 by German naturalist Christian Gottfried Ehrenberg. A classical plural sometimes also erroneously used as a singular.
The Greek word is from a PIE *bak- "staff used for support, peg" (compare Latin baculum "rod, walking stick;" Irish bacc, Welsh bach "hook, crooked staff;" Middle Dutch pegel "peg, pin, bolt"). De Vaan writes, "Since *b was very rare in PIE, and Celtic shows an unexplained geminate, we are probably dealing with a loanword from an unidentified source."
The Medieval Latin word is of uncertain origin; perhaps ultimately from Latin baculum "staff" (see bacillus), which the young student might carry. Or it might be a re-Latinization of bachelor in its academic sense.
In modern U.S. usage, baccalaureate usually is short for baccalaureate sermon (1864), a religious farewell address to a graduating class at an American college, from the adjectival sense "pertaining to the university degree of bachelor."
"disaster," 1848, from French débâcle "downfall, collapse, disaster" (17c.), a figurative use, literally "breaking up (of ice on a river) in consequence of a rise in the water," extended to the violent flood that follows when the river ice melts in spring; from débâcler "to free," earlier desbacler "to unbar," from des- "off" (see dis-) + bacler "to bar," from Vulgar Latin *bacculare, from Latin baculum "stick" (see bacillus).
The literal sense is attested in English from 1802, in geology, to explain the landscapes left by the ice ages. Figurative sense of "disaster" was present in French before English borrowed the word.
1540s, imbecille "weak, feeble" (especially in reference to the body), from French imbecile "weak, feeble" (15c.), from Latin imbecillus "weak, feeble," a word of uncertain origin.
The Latin word traditionally is said to mean "unsupported" or "without a walking stick" (Juvenal: imbecillis: quasi sine baculo), from assimilated form of in- "not, opposite of" + baculum "a stick" (see bacillus), but Century Dictionary finds that "improbable" and de Vaan finds it "very far-fetched" and adds "it seems to me that exactly the persons who can walk without a support are the stronger ones." There also are phonological objections.
Sense shifted to "mentally weak or incapable" from mid-18c. (compare frail, which in provincial English also could mean "mentally weak"). As a noun, "feeble-minded person," it is attested from 1802. Traditionally an adult with a mental age of roughly 6 to 9 (above an idiot but beneath a moron).
"pointed pin of wood, metal, or other material," mid-15c., pegge, from Middle Dutch pegge "peg," or a similar Low German word (Low German pigge "peg," German Pegel "gauge rod, watermark," Middle Dutch pegel "little knob used as a mark," Dutch peil "gauge, watermark, standard"); of uncertain origin; perhaps from PIE *bak- "staff used as support" (see bacillus).
To be a square peg in a round hole (or the reverse) "be inappropriate for one's situation" is attested by 1836; to take someone down a peg "humble, lower the esteem of" is from 1580s, but the original literal sense is uncertain (most of the sensibly plausible candidates are not attested until centuries later). Peg leg "wooden leg of the simplest form" is attested from 1765.