Definition of American arborvitae
: an evergreen tree ( Thuja occidentalis) of eastern North America that has a conical or columnar form, reddish-brown bark, flattened branchlets in horizontal planes with closely attached scalelike leaves, and soft, decay-resistant wood and that has numerous ornamental cultivars — called also
eastern arborvitae, eastern white cedar, swamp cedar, northern white cedar, white cedar, yellow cedar; compare oriental arborvitae
