lath /lɑːθ/noun 3verb 1forms 3 noun3 •A thin, narrow strip, fastened to the rafters, studs, or floor beams of a building, for the purpose of supporting a covering of tiles, plastering, etc.It is a piece of wood furnished with two parallel rows of plates, folding over each other, so as to resemble, in some degree, the laths of a blind. — 1847 •One of the sharp-edged, thick planks driven forward to hold back loose earth or mud when digging the way through for tunnelling or spiling. Also called a spill. •Microscopic, needle-like crystals, usually of plagioclase feldspar, in a glassy groundmass verb1 •To cover or line with laths. formslathed · lathing · laths