The Collaborative International Dictionary of English v.0.48:

Sainfoin \Sain"foin\ (?; 277), n. [F., fr. sain wholesome (L.
   sanus; see Sane.) + foin hay (L. faenum); or perh. fr.
   saint sacred (L. sanctus; see Saint) + foin hay.] (Bot.)
   (a) A leguminous plant (Onobrychis sativa) cultivated for
       fodder. [Written also saintfoin.]
   (b) A kind of tick trefoil (Desmodium Canadense). [Canada]
       [1913 Webster]

WordNet (r) 3.0 (2006):

sainfoin
    n 1: Eurasian perennial herb having pale pink flowers and curved
         pods; naturalized in Britain and North America grasslands
         on calcareous soils; important forage crop and source of
         honey in Britain [syn: sainfoin, sanfoin, holy
         clover, esparcet, Onobrychis viciifolia, Onobrychis
         viciaefolia]