ETYM Old Eng. lengthe, AS. length, from lang, long, long; akin to Dutch lengte, Dan. laengde, Swed. längd, Icel. lengd. Related to Long.
1. A section of something that is long and narrow.
2. The linear extent in space from one end to the other; the longest horizontal dimension of something that is fixed in place.
3. The property of being the extent of something from beginning to end.

The number of linear units of storage space occupied by an object, such as a file on disk or a data structure in a program, typically measured in bits, bytes, or blocks.