Etymology: < Anglo-Norman plauncke, Anglo-Norman and Old French regional (northern) planke, Old French regional (northern) planque (second half of the 12th cent.; Middle French, French regional (chiefly northern) planque ), variant of Old French planche little wooden bridge (1150), plank, slab (second half of 12th cent.), cultivated strip of land in a garden (1293; Middle French, French planche ) < classical Latin or post-classical Latin planca board, plank, slab (3rd cent. a.d. or earlier: see note), in post-classical Latin also measure of land (10th cent.), horseshoe (13th cent. in a British source), probably < post-classical Latin palanca (see palank n.), perhaps influenced by classical Latin plānus plain adj.² Compare Old Occitan planca , plancha (late 12th cent.; Occitan planca ), Catalan planca (998 in a Latin context; now regional), both in sense ‘footbridge, gangplank’, Portuguese prancha plank, board (15th cent.), Italian regional pianca board (16th cent. in sense ‘workbench’); also Old Frisian plonke , Middle Dutch planke (Dutch plank ), Middle Low German planke , Middle High German planke (German Planke ), Old Swedish planka (Swedish planka ). Compare planch n.The dating and origin of Latin planca are uncertain. It is recorded in an 8th-cent. epitome of a 2nd-cent. grammarian, glossed tabula plana flat plank or board, and it has been restored in two inscriptions, where it apparently denotes a board or slab placed on a grave (compare sense 3a). Tertullian (late 2nd or early 3rd cent.) has planca salutis plank of safety (compare sense 1c). Palladius (4th cent.) refers to planks which are roboreae ‘made of oak’. Post-classical Latin planca in the sense ‘plank’ is frequent 1172–1472 in British sources. Attested earlier in a surname: Willelmus de la Plank' , although it is unclear whether this is to be interpreted as reflecting the Middle English or the Anglo-Norman word. In plank buttress n. at Compounds 2 after German Plankengerüst ( A. F. W. Schimper Pflanzengeographie (1898) III. iv. 328).

Etymology: < plank n. Compare post-classical Latin plancare , planchere , planchiare , plangiare , plangchiare (from late 12th cent. in British sources), Middle French (Tournai) planquier (1486), Old French planchier to lay a floor, to plank, to bridge (c1170; Middle French planchier , plancher , French †plancher ; compare Old French planchoier , Middle French, French planchéier ), Middle French planchier to cultivate an allotment (1364), Old Occitan plancar (Occitan plancar ); also Middle Dutch planken (Dutch planken ), Middle Low German planken , Middle High German planken (German -planken , now only in prefixed forms), Old Swedish planka (Swedish planka ). Compare planch v.In sense 2 perhaps originally a different word. With sense 2b compare earlier plunk v.¹ 2 and later plonk v. 2.