coul·ter or col·ter (kōltər)
A blade or wheel attached to the beam of a plow that makes vertical cuts in the soil in advance of the plowshare.
[Middle English culter, from Old English culter and Old French coltre, both from Latin culter, knife, plowshare; see skel-1 in the Appendix of Indo-European roots.]
(click for a larger image)coulter
round coulter blade (left) in front of a moldboard
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.