Definition of "plumb line" []

• A line from which a weight is suspended to determine verticality or depth. (noun)
• A line regarded as directed exactly toward the earth's center of gravity. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.