oak

Concise Oxford English Dictionary © 2008 Oxford University Press:
oak/əʊk/

▶noun

• 1 a large tree which bears acorns and typically has lobed leaves and hard durable wood. [Genus Quercus: many species.]

  ■ used in names of other trees or plants resembling this, e.g. poison oak.

• 2 a smoky flavour or nose characteristic of wine aged in oak barrels.

– phrases
sport the (or one's) oak Brit. (in certain universities) shut the outer door of one's room as a sign that one does not wish to be disturbed. [such doors were often formerly made of oak.]

– derivatives
oaken adjective (archaic),
oaky adjective .

– origin OE āc, of Gmc origin.