1. (n.) Any tree or shrub of the genus Quercus. The oaks have alternate leaves, often variously lobed, and staminate flowers in catkins. The fruit is a smooth nut, called an acorn, which is more or less enclosed in a scaly involucre called the cup or cupule. There are now recognized about three hundred species, of which nearly fifty occur in the United States, the rest in Europe, Asia, and the other parts of North America, a very few barely reaching the northern parts of South America and Africa. Many of the oaks form forest trees of grand proportions and live many centuries. The wood is usually hard and tough, and provided with conspicuous medullary rays, forming the silver grain.

2. (n.) The strong wood or timber of the oak.

Gibraltar acacia adamant ailanthus alder alligator pear allspice almond apple apricot ash aspen avocado balsa balsam banyan bass basswood bay bayberry beech beechwood betel palm birch bone brick buckeye burl butternut buttonwood cacao candleberry cashew cassia catalpa cement cherry chestnut chinquapin cinnamon citron clove coconut concrete cork cork oak cypress diamond dogwood ebony elder elm eucalyptus fig fir flint frankincense granite grapefruit guava gum gumwood hawthorn hazel heart of oak hemlock henna hickory holly hop tree horse horse chestnut iron ironwood juniper kumquat laburnum lancewood larch laurel lemon lime linden lion litchi litchi nut locust logwood magnolia mahogany mango mangrove maple marble medlar mountain ash mulberry nails nutmeg olive orange ox palm papaw papaya peach pear pecan persimmon pine pistachio plane plum pomegranate poplar quince raffia palm rain tree redwood rock sandalwood sassafras senna sequoia spruce steel stone sumac sycamore tangerine teak tulip tree walnut willow witch hazel yew