The Collaborative International Dictionary of English v.0.48:
Weeder \Weed"er\, n. One who, or that which, weeds, or frees from anything noxious. [1913 Webster]WordNet (r) 3.0 (2006):
weeder n 1: a farmhand hired to remove weeds 2: a hand tool for removing weeds [syn: weeder, weed- whacker]