1.  weeder(n = noun.person) - a farmhand hired to remove weeds;
is a kind of farm worker, farmhand, field hand, fieldhand
Derived form verb weed₁

2.  weeder(n = noun.artifact) weed-whacker - a hand tool for removing weeds;
is a kind of hand tool
Derived form verb weed₁

   One who, or that which, weeds, or frees from anything noxious. [1913 Webster]