Also known as lathing strips, pieces of lumber approx. 1/4" x1 1/2" used as a support structure for plaster walls.
plaster lath: Houses: CapeLinks Cape Cod Photos
Lathing strips are still available at lumber yards and home centers and have many theatrical uses.
Lath, Lath Strips, Sticks, Lumber Stacking, Wood Strips from DSL Mills in British Columbia
Also may refer to metal mesh used instead of wood to support walls and ceilings after 1950.