Lewis & Short

faenārĭus (less correctly fēn-, foen-), a, um, adj. [faenum], of or for hay, hay-: falces, Cato, R. R. 10, 3; Varr. L. L. 5, 31, 38.
As subst.: faenārĭus, ĭi, m., a seller of hay, a hay salesman, Inscr. ap. Grut. 175, 9.