Meaning

• A piece of lead attached to a line, used in sounding the depth of water, a plumb bob or a plumb line

• Hence, any weight

• A piece of lead formerly used by school children to rule paper for writing (that is, to mark with rules, with lines)

• A plummet line, a line with a plummet; a sounding line

• Violent or dramatic fall

• A decline; a fall; a drop

Meaning

• To drop swiftly, in a direct manner; to fall quickly.

  "After its ascent, the arrow plummeted to earth."