plumb-line

n line with a plumb(1) attached to one end 铅垂线.

plonk, plop, plosive, plot, plough, plough (US plow), ploughman (US plowman), ploughshare (US plowshare) (also share), plover, plow, ploy, pluck, pluckily, plucky, plug, plug-hole, plum, plum pudding, plumage, plumb, plumber, plumbing, plume, plummet, plummy, plump, plumpness, plunder, plunderer, plunge, plunger, plunk, pluperfect, plural, pluralism, pluralist, pluralist (also pluralistic), plurality, plus, plus-fours,