اسم ( noun )• : تعریف: a line with a lead weight attached to it that is lowered into water to measure its depth.
• (nautical) plumb line use to determine depth of water(nautical) plumb line use to determine depth of water, plumb line used in sounding
in electronics means پایه. خط اتصالعمق سنجtake lead line & tell me how feet deep is the ocean+ عکس و لینک