From WordNet (r) 3.0 (2006) :
gill-over-the-ground
n 1: trailing European aromatic plant of the mint family having
rounded leaves and small purplish flowers often grown in
hanging baskets; naturalized in North America; sometimes
placed in genus Nepeta [syn: ground ivy, alehoof,
field balm, gill-over-the-ground, runaway robin,
Glechoma hederaceae, Nepeta hederaceae]