the GNU version of the Collaborative International Dictionary of English
n. See lucern, the plant.
The Century Dictionary and Cyclopedia
n. A leguminous plant, Medicago sativa, a highly valuable pasture- and forage-plant, cultivated from ancient times, now widely spread in temperate climates.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. important European leguminous forage plant with trifoliate leaves and blue-violet flowers grown widely as a pasture and hay crop
Word Usage
"Of the legumes, alfalfa, also called lucerne, is the most popular crop; it's estimated that more than half of the hay harvested in the United States is alfalfa, or an alfalfa/grass mix."