1) A lath made from the wood at the centre or heart of the tree, hardened by age.
The term is on record long before ‘heart-wood’ which has not been noted earlier than 1801. In many examples, lath has the dialect spelling ‘latt’: 1441-2 60 hertlattis 5d, Selby
1463 Et de quodam extraneo vendente hertlatt’ super Statham contra ordinacionem civitatis, vjd, York
1521 paid for ij bunche of hert lattes vijd, York
1610 seven hundreth of hart lattes, Kirkstall
1733 hart laths, sap laths and slate pin wood, Wakefield.