coulter
/ˈkəʊltə(r)/( <美> colter)
noun
1- a vertical cutting blade fixed in front of a ploughshare犁刀。
1.1
- the part of a seed drill that makes the furrow for the seed（犁沟播种用的）播种机刀。
词源
Old English, from Latin culter 'knife or ploughshare'.