plummet
a lead plumb used by anglers to determine the depth of water
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
plummet
[′pləm·ət] (engineering)
A loose-fitting metal plug in a tapered rotameter tube which moves upward (or downward) with an increase (or decrease) in fluid flow rate upward through the tube. Also known as float.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
plumb bob, plummet
A shaped metal weight which is suspended from the lower end of a line to determine the vertical. (See illustration p. 744.)
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.