The Collaborative International Dictionary of English v.0.48:

Mascle \Mas"cle\ (m[a^]s"k'l), n. [OF. mascle, F. macle, L.
   macula spot, mesh of a net, LL. macula, macla, mascla a scale
   of a coat of mail. See Mail armor.] (Her.)
   A lozenge voided.
   [1913 Webster]