Source : Webster's Revised Unabridged Dictionary (1913)

Weedless \Weed"less\, a.
   Free from weeds or noxious matter.

Weedless \Weed"less\, a.
   Free from weeds; -- said of a kind of motor-boat propeller
   the blades of which curve backwardly, as respects the
   direction of rotation, so that they draw through the water,
   and so do not gather weeds with which they come in contact.

Source : WordNet®

weedless
     adj : free from weeds; "a weedless garden" [ant: {weedy}]