Plank
Middle English: from Old Northern French planke, from late Latin planca ‘board’, feminine (used as a noun) of plancus ‘flat-footed’.
wiktionary
From Middle English plank, planke, borrowed from Old French planke, Old Northern French planque (compare French planche, from Old French planche), from Vulgar Latin planca, from palanca, from Latin phalanga. The Latin term derives from the Ancient Greek φάλαγξ(phálanx), so it is thus a doublet of phalange and phalanx. Compare also the doublet planch, borrowed later from Middle French.
etymonline
plank (n.)
late 13c. (c. 1200 as a surname), "thick board used in construction," from Old North French planke, a 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 a nasalized variant of PIE root *plak- (1) "to be flat." Planche itself was also used in Middle English.
Technically, timber sawed to measure 2 to 6 inches thick, 9 inches or more wide, and 8 feet or more long. The political sense of "article or paragraph formulating a distinct principle in a party platform" is U.S. coinage from 1848, based on the double sense of platform. To be made to walk the plank, "be forced to walk along a plank laid across the bulwarks of a ship until one reaches the end and falls into the sea," popularly supposed to have been a pirate form of execution, is attested from 1789, and most early references are to slave-ships disposing of excess human cargo in crossing the ocean.
plank (v.)
"to cover or lay with planks," early 15c., from plank (n.). Related: Planked; planking.
