Merlon

from WordNet (r) 3.0 (2006)

merlon
    n 1: a solid section between two crenels in a crenelated
         battlement

from The Collaborative International Dictionary of English v.0.48

Merlon \Mer"lon\, n. [F., perh. fr. L. moerus, for murus a wall,
   through (assumed) dim. moerulus.] (Fort.)
   One of the solid parts of a battlemented parapet; a
   battlement. See Illust. of {Battlement}.
   [1913 Webster]