Waxwood is a rare kind of wood that exists in RuneScape. It was first referenced to in A Void Dance whereupon it is found in Karamja while investigating an escaped pest. The player claims that they have never come across it before, and Jessika notes that it is "ugly and un-treatable", and is not widely used as a material for making anything, though it is naturally waterproof, hence its name, and is often used to seal things in water-tight containers.
Rommik, the owner of the Crafting shop Rommik's Crafty Supplies in Rimmington, also takes an order for several boxes made of Waxwood. He says that it "broke this crafter's heart to do so" meaning that he found working with Waxwood contemptable.
Later, it is revealed that the Waxwood was used in making sealed boxes which were unopenable, but which contained "foodgoo", a kind of substance which void leeches use to drain the energy from all living things around them, including humans. Boxes full of it were sold by Ali Tist to the people of Falador in a plot by the Kinshra to overthrow the White Knights.