In geometric measurements, length most commonly refers to the longest dimension of an object.
In certain contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured. For example it is possible to cut a length of a wire which is shorter than wire thickness. Another example is FET transistors, in which the channel width may be larger than channel length.
Length may be distinguished from height, which is vertical extent, and width or breadth, which are the distance from side to side, measuring across the object at right angles to the length.
Length is a measure of one dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed). In most systems of measurement, the unit of length is a fundamental unit, from which other units are defined.
Famous quotes containing the word length:
“The grace of novelty and the length of habit, though so very opposite to one another, yet agree in this, that they both alike keep us from discovering the faults of our friends.”
—François, Duc De La Rochefoucauld (1613–1680)
“Rivers must have been the guides which conducted the footsteps of the first travelers. They are the constant lure, when they flow by our doors, to distant enterprise and adventure; and, by a natural impulse, the dwellers on their banks will at length accompany their currents to the lowlands of the globe, or explore at their invitation the interior of continents.”
—Henry David Thoreau (1817–1862)
“He thought he saw an Elephant,
That practiced on a fife:
He looked again, and found it was
A letter from his wife.
“At length I realize,” he said,
“The bitterness of Life!””
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)