An acorn is the fruit of the oak tree. By analogy with the shape, in nautical language, the word also refers to a piece of wood keeping the vane on the mast-head. The etymology of the word (earlier akerne, and acharn) is discussed in the Oxford English Dictionary. It is derived from a word (Goth akran) which meant "fruit," originally "of the unenclosed
land," and so of the most important forest produce, the oak.
Chaucer speaks of "achornes of okes." By degrees, popular
etymology connected the word both with "corn" and "oak-horn," and the spelling changed accordingly.
Acorns take up to three years to mature and appear only on adult trees, and thus are often a symbol of patience and the fruition of long, hard labor. For example, an English proverb states that Great oaks from little acorns grow, urging the listener to wait for maturation of a project or idea. A German folktale has a farmer outwit Satan, to whom he has promised his soul, by asking for a reprieve until his first crop is harvested; he plants acorns and has several years to enjoy first.
Based on article from 1911 EB
Cultural aspects
For computers, see Acorn, Ltd.