larch UK /ˈlɑːtʃ/US /ˈlɑɹt͡ʃ/ noun2 •A coniferous tree, of genus Larix, having deciduous leaves in fascicles.The Gummy Larch-Tree, and the Thapsos there, Wound-wort and Maiden-weed, perfume the Air. — 1716 •Wood of the larch. formslarches