colter
noun
col·ter
variants or less commonly coulter
ˈkōltə(r) 
plural -s
: a knife, sharp disc, or other cutting tool that is attached to the beam of a plow to cut the sward in advance of the plowshare and moldboard
Word History
Etymology
Middle English colter, from Old English culter & Old French coltre, both from Latin culter plowshare, knife; akin to Old High German scala husk, Old Norse skilja to separate, Gothic skilja butcher, Greek skalis hoe, mattock, Lithuanian skélti to split