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:
“When I had mapped the pond ... I laid a rule on the map lengthwise, and then breadthwise, and found, to my surprise, that the line of greatest length intersected the line of greatest breadth exactly at the point of greatest depth.”
—Henry David Thoreau (1817–1862)
“They raise their minds by brooding over and embellishing their sufferings, from one degree of fervid exaltation and dreary greatness to another, till at length they run amuck entirely, and whoever meets them would do well to run them thro’ the body.”
—Thomas Carlyle (1795–1881)
“And my spirit is grown to a lordly great compass within,
That the length and the breadth and the sweep of the marshes of
Glynn
Will work me no fear like the fear they have wrought me of yore
When length was failure, and when breadth was but bitterness sore,
And when terror and shrinking and dreary unnamable pain
Drew over me out of the merciless miles of the plain,—
Oh, now, unafraid, I am fain to face
The vast sweet visage of space.”
—Sidney Lanier (1842–1881)