plumb line

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a cord from which a metal weight is suspended pointing directly to the earth's center of gravity;
used to determine the vertical from a given point (Freq. 1)
• Syn:
perpendicular
• Hypernyms:
cord
• Hyponyms:
lead line, sounding line, plumb rule
• Part Meronyms:
plumb bob, plumb, plummet