An oak is a tree that typically sheds its leaves in the winter and grows acorns as fruit. If you get hit on the head with an acorn, you are probably standing under an oak.

There are many species of oaks, a few of which are evergreen, keeping their leaves all year, but most have bright leaves in the fall and are bare for the winter months. An oak table or oak desk is made from the sturdy wood of an oak tree. The strength of oaks has inspired several countries to adopt them as symbols on money and flags, and in 2004 the oak was voted the national tree by the US Congress.

Definitions of oak

n a deciduous tree of the genus Quercus; has acorns and lobed leaves

“great oaks grow from little acorns”
oak tree
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live oak
any of several American evergreen oaks
white oak
any of numerous Old World and American oaks having 6 to 8 stamens in each floret, acorns that mature in one year and leaf veins that never extend beyond the margin of the leaf
European turkey oak, Quercus cerris, turkey oak
large deciduous tree of central and southern Europe and Asia Minor having lanceolate leaves with spiked lobes
Quercus coccinea, scarlet oak
medium-large deciduous tree with a thick trunk found in the eastern United States and southern Canada and having close-grained wood and deeply seven-lobed leaves turning scarlet in autumn
Quercus ellipsoidalis, jack oak, northern pin oak
small to medium deciduous oak of east central North America; leaves have sharply pointed lobes
red oak
any of numerous American oaks having 4 stamens in each floret, acorns requiring two years to mature and leaf veins usually extending beyond the leaf margin to form points or bristles
Quercus ilex, evergreen oak, holly-leaved oak, holm oak, holm tree
evergreen oak of southern Europe having leaves somewhat resembling those of holly; yields a hard wood
Quercus imbricaria, laurel oak, shingle oak
small deciduous tree of eastern and central United States having leaves that shine like laurel; wood is used in western states for shingles
Quercus incana, bluejack oak, turkey oak
small semi-evergreen shrubby tree of southeastern United States having hairy young branchlets and leaves narrowing to a slender bristly point
California black oak, Quercus kelloggii
large deciduous tree of the Pacific coast having deeply parted bristle-tipped leaves
American turkey oak, Quercus laevis, turkey oak
small slow-growing deciduous shrubby tree of dry sandy barrens of southeastern United States having leaves with bristle-tipped lobes resembling turkey's toes
Quercus laurifolia, laurel oak, pin oak
large nearly semi-evergreen oak of southeastern United States; thrives in damp soil
Quercus lyrata, overcup oak
medium-large deciduous timber tree of central and southern United States; acorns deeply immersed in the cup and mature in first year
scrub oak
any of various chiefly American small shrubby oaks often a dominant form on thin dry soils sometimes forming dense thickets
Japanese oak, Quercus grosseserrata, Quercus mongolica
oak with moderately light fine-grained wood; Japan
chestnut oak
an oak having leaves resembling those of chestnut trees
Quercus nigra, possum oak, water oak
relatively tall deciduous water oak of southeastern United States often cultivated as a shade tree; thrives in wet soil
Nuttall oak, Nuttall's oak, Quercus nuttalli
similar to the pin oak; grows in damp sites in Mississippi River basin
Quercus palustris, pin oak, swamp oak
fast-growing medium to large pyramidal deciduous tree of northeastern United States and southeastern Canada having deeply pinnatifid leaves that turn bright red in autumn; thrives in damp soil
Quercus phellos, willow oak
medium to large deciduous oak of the eastern United States having long lanceolate leaves and soft strong wood
Quercus stellata, box white oak, brash oak, iron oak, post oak
small deciduous tree of eastern and central United States having dark green lyrate pinnatifid leaves and tough moisture-resistant wood used especially for fence posts
Quercus suber, cork oak
medium-sized evergreen oak of southern Europe and northern Africa having thick corky bark that is periodically stripped to yield commercial cork
Quercus texana, Spanish oak
small deciduous tree having the trunk branched almost from the base with spreading branches; Texas and southern Oklahoma
Chinese cork oak, Quercus variabilis
medium to large deciduous tree of China, Japan, and Korea having thick corky bark
Quercus velutina, black oak, quercitron, quercitron oak, yellow oak
medium to large deciduous timber tree of the eastern United States and southeastern Canada having dark outer bark and yellow inner bark used for tanning; broad five-lobed leaves are bristle-tipped
California live oak, Quercus agrifolia, coast live oak
highly variable often shrubby evergreen oak of coastal zone of western North America having small thick usually spiny-toothed dark-green leaves
American white oak, Quercus alba
large slow-growing deciduous tree of the eastern United States having stout spreading branches and leaves with usually 7 rounded lobes; yields strong and durable hard wood
Arizona white oak, Quercus arizonica
semi-evergreen shrub or small tree of Arizona and New Mexico having acorns with hemispherical cups
Quercus bicolor, swamp oak, swamp white oak
large deciduous oak of the eastern United States with a flaky bark and leaves that have fewer lobes than other white oaks; yields heavy strong wood used in construction; thrives in wet soil
Quercus chrysolepis, canyon live oak, canyon oak, iron oak, maul oak
medium-sized evergreen of southwestern United States and northwestern Mexico with oblong leathery often spiny-edged leaves
Quercus falcata, southern red oak, swamp red oak, turkey oak
large round-topped deciduous tree with spreading branches having narrow falcate leaves with deeply sinuate lobes and wood similar to that of northern red oaks; New Jersey to Illinois and southward
Garry oak, Oregon oak, Oregon white oak, Quercus garryana
small deciduous tree of western North America with crooked branches and pale grey bark
Quercus ilicifolia, bear oak
shrubby oak of southeastern United States usually forming dense thickets
California white oak, Quercus lobata, roble, valley oak, valley white oak
tall graceful deciduous California oak having leathery leaves and slender pointed acorns
Quercus macrocarpa, bur oak, burr oak, mossy-cup oak, mossycup oak
medium to large deciduous oak of central and eastern North America with ovoid acorns deeply immersed in large fringed cups; yields tough close-grained wood
Quercus marilandica, blackjack, blackjack oak, jack oak
a common scrubby deciduous tree of central and southeastern United States having dark bark and broad three-lobed (club-shaped) leaves; tends to form dense thickets
Quercus michauxii, swamp chestnut oak
medium to large deciduous tree of moist areas of southeastern United States similar to the basket oak
Quercus muehlenbergii, chinkapin oak, chinquapin oak, yellow chestnut oak
medium-sized deciduous tree of the eastern United States that yields a strong durable wood
Quercus myrtifolia, myrtle oak, seaside scrub oak
small evergreen shrub or tree of southeastern United States; often forms almost impenetrable thickets in sandy coastal areas
Quercus petraea, Quercus sessiliflora, durmast
deciduous European oak valued for its tough elastic wood
Quercus montana, Quercus prinus, basket oak, cow oak
medium to large deciduous tree of the eastern United States; its durable wood is used as timber or split and woven into baskets or chair seats
Quercus prinoides, dwarf chinkapin oak, dwarf chinquapin oak, dwarf oak
deciduous shrubby tree of northeastern and central United States having a sweet edible nut and often forming dense thickets
English oak, Quercus robur, common oak, pedunculate oak
medium to large deciduous European oak having smooth leaves with rounded lobes; yields hard strong light-colored wood
Quercus borealis, Quercus rubra, northern red oak
large symmetrical deciduous tree with rounded crown widely distributed in eastern North America; has large leaves with triangular spiny tipped lobes and coarse-grained wood less durable than that of white oaks
Quercus shumardii, Shumard oak, Shumard red oak
large deciduous red oak of southern and eastern United States having large seven-lobed to nine-lobed elliptical leaves, large acorns and medium hard coarse-grained wood
Quercus virginiana, southern live oak
medium-sized evergreen native to eastern North America to the east coast of Mexico; often cultivated as shade tree for it wide-spreading crown; extremely hard tough durable wood once used in shipbuilding
Quercus wislizenii, Quercus wizlizenii, interior live oak
a small shrubby evergreen tree of western North America similar to the coast live oak but occurring chiefly in foothills of mountain ranges removed from the coast; an important part of the chaparral
Type of:
a tall perennial woody plant having a main trunk and branches forming a distinct elevated crown; includes both gymnosperms and angiosperms

n the hard durable wood of any oak; used especially for furniture and flooring

fumed oak
oak given a weathered appearance by exposure to fumes of ammonia; used for cabinetwork
holm oak
hard wood of the holm oak tree
Type of:
the hard fibrous lignified substance under the bark of trees

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