cantyoudaoicibaDictYouDict[cant 词源字典]
cant: English has two separate words cant. The older, ‘oblique angle’ [14], originally meant ‘edge’, and appears to have come via Middle Low German kant or Middle Dutch cant, both meaning ‘edge’ or ‘corner’, from Vulgar Latin *canto, a descendant of Latin cantus ‘iron tyre’. which was probably of Celtic origin (Welsh cant means ‘rim’).

The accusative case of the Vulgar Latin word, *cantōnem, was the source of English canton [16], originally ‘corner, section’, now ‘territorial division’; while its Italian descendant, canto, may be the source of Italian cantina ‘cellar’, from which English got canteen [18]. Cant ‘thieves’ jargon’ or ‘hypocritical talk’ [16] was probably originally a specific application of the Latin verb cantāre ‘sing’ (source also of English chant, canto, cantor, cantata, and canticle).

It is usually assumed that the usage derives from an ironic transference of the singing of church congregations or choirs to the wheedling ‘song’ of beggars and (by association) thieves.
=> canteen, canton; cantata, cantor, chant[cant etymology, cant origin, 英语词源]
cant (n.1)youdaoicibaDictYouDict
"insincere talk," 1709, earlier it was slang for "whining of beggars" (1640s), from the verb in this sense (1560s), from Old North French canter (Old French chanter) "to sing, chant," from Latin cantare, frequentative of canere "to sing" (see chant (v.)). Sense in English developed after 1680 to mean the jargon of criminals and vagabonds, thence applied contemptuously by any sect or school to the phraseology of its rival.
... Slang is universal, whilst Cant is restricted in usage to certain classes of the community: thieves, vagrom men, and -- well, their associates. ... Slang boasts a quasi-respectability denied to Cant, though Cant is frequently more enduring, its use continuing without variation of meaning for many generations. [John S. Farmer, Forewords to "Musa Pedestris," 1896]
cant (n.2)youdaoicibaDictYouDict
"slope, slant," late 14c., Scottish, "edge, brink," from Old North French cant "corner" (perhaps via Middle Low German kante or Middle Dutch kant), from Vulgar Latin *canthus, from Latin cantus "iron tire of a wheel," possibly from a Celtic word meaning "rim of wheel, edge" (compare Welsh cant "bordering of a circle, tire, edge," Breton cant "circle"), from PIE *kam-bo- "corner, bend," from root *kemb- "to bend, turn, change" (cognates: Greek kanthos "corner of the eye," Russian kutu "corner").