length / leng(k)[unvoicedth]; lenth/ • n. 1. the measurement or extent of something from end to end; the greater of two or the greatest of three dimensions of a body: it can reach over two feet in length the length of the airport terminal. ∎  the amount of time occupied by something: delivery must be within a reasonable length of time. ∎  the quality of being long: the length of the waiting list. ∎  the full distance that a thing extends for: the muscles running the length of my spine. ∎  the extent of a garment in a vertical direction when worn: the length of her skirt. ∎  Prosody & Phonet. the metrical quantity or duration of a vowel or syllable.2. the extent of something, esp. as a unit of measurement, in particular: ∎  the length of a swimming pool as a measure of the distance swum: fifty lengths of the pool. ∎  the length of a horse, boat, etc., as a measure of the lead in a race: the mare won the race last year by seven lengths. ∎  (one's length) the full extent of one's body: he awkwardly lowered his length into the small car.3. (in bridge or whist) the number of cards of a suit held in one's hand, esp. when five or more.4. a stretch or piece of something: a stout length of wood.5. a degree or extreme to which a course of action is taken: they go to great lengths to avoid the press. PHRASES: at length1. in detail; fully: these aspects have been discussed at length.2. after a long time: at length she laid down the pencil.the length and breadth of the whole extent of: women from the length and breadth of Russia.

length
1. of a sequence. The cardinality of the domain of the sequence. Thus the sequence a₁,a₂,…,a_n

has length n.

2. of a string. The upper bound of the string, hence the number of elements in the string.

3. of a vector. The number of elements in the vector.

length OE. lengðu (rare; usu. lengu, lenge) = Du. lengte, ON. lengd :- Gmc. *laŋgiþō, f. *laŋgaz LONG1; see -TH1.
Hence lengthen XVI see -EN5. lengthy XVII.