lath (n.) Look up lath at
"thin strip of wood" used chiefly in roof-building and plastering, late 13c., probably from an unrecorded Old English *læððe, variant of lætt "beam, lath," which is apparently from a Proto-Germanic *laþþo (source also of Old Saxon, Old Norse latta, Middle Dutch, German latte "lath," Dutch lat, Middle High German lade "plank," which is the source of German Laden "counter," hence, "shop"), but there are phonetic difficulties.
lath (v.) Look up lath at
"to cover or line with laths," 1530s, from lath (n.). Related: Lathed; lathing.