twelvepenny nail

twelve·pen·ny nail

 (twĕlv′pĕn′ē)
n.
A nail 3.5 inches (8.25 centimeters) long.

[From the original price per hundred.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.