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)
“At length he would call to let us know where he was waiting for us with his canoe, when, on account of the windings of the stream, we did not know where the shore was, but he did not call often enough, forgetting that we were not Indians.... This was not because he was unaccommodating, but a proof of superior manners. Indians like to get along with the least possible communication and ado. He was really paying us a great compliment all the while, thinking that we preferred a hint to a kick.”
—Henry David Thoreau (1817–1862)
“The value of life lies not in the length of days but in the use you make of them; he has lived for a long time who has little lived.”
—Michel de Montaigne (1533–1592)