lath / la[unvoicedth]/ • n. (pl. laths / la[voicedth]z; la[unvoicedth]s/ ) a thin flat strip of wood, esp. one of a series forming a foundation for the plaster of a wall or the tiles of a roof, or made into a trellis or fence. ∎  laths collectively as a building material, esp. as a foundation for supporting plaster.• v. [tr.] cover (a wall or ceiling) with laths.

lath OE. lætt (corr. to MDu. latte, Du. lat, G. dial latz) survives in mod. dial. lat, but began to be replaced XIV in general use by lat(h)the, which appears to repr. an OE. *lœðð-, corr. to OHG. latta (G. latte); ult. relations obscure.

lath.
1. Narrow, thin strip of wood used as a base for a plaster finish.

2. Slightly larger timber, more a batten or firring-strip secured to beams, rafters, studs, etc., as a fixing for tiles, slates, or other finish.