Source : Webster's Revised Unabridged Dictionary (1913)

Tr'efl'e \Tr['e]`fl['e]"\, a. [F. tr['e]fl['e]. See {Trefoil}.]
   (Her.)
   Having a three-lobed extremity or extremities, as a cross;
   also, more rarely, ornamented with trefoils projecting from
   the edges, as a bearing.