The Collaborative International Dictionary of English v.0.48:

M'etayer \M['e]`ta`yer"\ (F. ?; E. ?), n. [F., fr. LL.
   medietarius, fr. L. medius middle, half. See Mid, a.]
   One who cultivates land for a share (usually one half) of its
   yield, receiving stock, tools, and seed from the landlord; a
   type of sharecropper. [France & Italy] --Milman.
   [1913 Webster + PJC]