plankyoudaoicibaDictYouDict[plank 词源字典]
plank: [13] The etymological idea underlying plank may be ‘flatness’. It comes via planke, a northern dialect version of Old French planche (source of English planchette [19]), from late Latin planca ‘slab’, a derivative of the adjective plancus ‘flat’. This may have come from the same source as Greek pláx ‘flat surface’, ancestor of English placenta.
=> planchette[plank etymology, plank origin, 英语词源]
plank (n.)youdaoicibaDictYouDict
late 13c. (c. 1200 as a surname), from Old North French planke, variant of Old French planche "plank, slab, little wooden bridge" (12c.), from Late Latin planca "broad slab, board," probably from Latin plancus "flat, flat-footed," from PIE *plak- (1) "to be flat" (see placenta). Technically, timber sawed to measure 2 to 6 inches thick, 9 inches or more wide, and 8 feet or more long. Political sense of "item of a party platform" is U.S. coinage from 1848. To walk the plank, supposedly a pirate punishment, is first attested 1789 and most early references are to slave-traders disposing of excess human cargo in crossing the ocean.