n.1 a a poisonous umbelliferous plant, Conium maculatum, with fernlike leaves and small white flowers. b a poisonous potion obtained from this.
2 (in full hemlock fir or spruce) a any coniferous tree of the genus Tsuga, having foliage that smells like hemlock when crushed. b the timber or pitch of these trees.
Etymology: OE hymlic(e)