a horizontal architectural member supporting the weight above an opening, as a window or a door.
Also, British, lintol.
Origin: 1350–1400; ME lyntel < MF lintel, dissimilated var. of *linter < L līmitāris orig., belonging to or indicating a boundary; later taken as synonym of līmināris orig., of the threshold. See limit, -ar1
[lin-tl] 
tl