span
Noun pluralspans
Pluralspans
- 1
- 2To extend across or reach over the distance between two points or sides.
The new suspension bridge spans the entire bay.
Her hand can span a full octave on the keyboard.
Similarcross, bridge, traverse, straddle, reach
Note
The verb has its own Old English ancestor, spannan, "to stretch," a cousin of German spannen; it was not formed from the noun. It takes a direct object and works naturally in the passive. William H. Prescott writes that "the rivers were spanned by arches of solid masonry." Bridges, arches and hands can all span things, and the subject is always whatever does the reaching.
- 3The distance covered by an arch, beam, girder, truss, roof, or bridge between its supports or abutments.
The main span of the suspension bridge stretches nearly a mile.
Builders added a central column because the roof's span was too great for unsupported timber.
Note
Engineers count bridges in spans: each stretch between piers or abutments is one. That is why Trains Illustrated, reporting the Severn Bridge disaster in January 1961, could write that "two spans of the bridge crashed down into the river." The longest is called the main span. The distance between supports largely decides how much a beam bends and deflects under load, so every designer has to reckon with it.
- 4A brief stretch of time or a small extent of space.
The company doubled its profits within a span of six months.
A short span of beach lay between the rocks and the pier.
Similarperiod, stretch, space, spell, interval
Note
A measure of the hand became a measure of life. George Farquhar's "Life's but a span; I'll every inch enjoy" (1699) plays the unit against inches, and Alexander Pope writes of "Earth's contracted Span." In everyday English the word is at home in attention span and in phrases like a span of six months, where it frames a stretch of time with a clear beginning and end.
- 5The distance between the wingtips of an aircraft or a bird.
The albatross has the greatest span of any living bird, sometimes exceeding eleven feet.
Engineers reduced the fighter's span so it could fit on the carrier's elevator.
Similarwingspan, wingspread
- 6A portion of something extending along its length; a continuous section or subsequence.
Crews replaced a damaged span of track north of the station.
The editor cut a long span of dialogue from the second act.
Similarsection, stretch, length, segment, portion
Note
Software gives this sense a precise job. In word processing, a span of text is a continuous run of characters that shares one style, meaning the same font and the same bold or italic. Robert Harris and Robert Warner use it this way in The Definitive Guide to SWT and JFace (2004). Outside software it covers any continuous section, such as a stretch of track or a passage of dialogue.
- 7An informal measure of length equal to the width of an outstretched hand, from the tip of the thumb to the tip of the little finger.
Lacking a tape measure, the carpenter sized up the board in spans.
The gap between the stones was barely a span wide.
Note
The bodily sense the others grow from: Old English spann, from a root meaning "to stretch," so the word first named the hand pulled wide. German Spanne and Dutch span are its cousins. Bridges, wings and lifetimes all borrowed this idea of a reach between two points. The pair-of-horses meaning is the exception, because it probably comes from a different Old English word.
- 8The stretch of a cable, wire, rope, or chain that runs from one support to the next.
Ice built up along one span of the transmission line until it snapped.
The cable car's final span stretches more than a kilometer between towers.
Similarstretch, length, section
Note
Line crews and cable-car engineers count their work this way: a transmission line or ropeway is a series of spans, each running tower to tower. How long each one is governs how far the line sags and how much tension it carries. Unlike the span of a bridge, which is rigid structure, this span hangs, so talk of it turns on sag, tension and the weight of ice.
- 9Any of various traditional units of length based on the handspan, especially the English unit of nine inches, one eighth of a fathom and equal to 22.86 centimeters.
A medieval survey recorded the wall as forty spans high.
Under the old English system, a span equaled half a cubit.
- 10To measure something by the width of the outstretched hand with the fingers extended, or with the fingers wrapped around the object.
The old farmer would span a beam with his outstretched hand to judge its width.
He spanned the horse's girth with both hands, his fingers meeting at the top.
Note
Measuring with the hand was once grand enough for scripture. The King James Bible of 1611 gives it cosmic scale: "my right hand hath spanned the heavens." The verb works in two ways. The fingers can spread across a distance, or they can wrap around something round, as when one spans a cylinder or a horse's girth.
- 11The set of all linear combinations of the vectors in a given set.
The span of the two basis vectors is the entire plane.
Because the third vector lies in the span of the first two, it adds nothing new.
Note
Linear algebra's noun for everything a set of vectors can reach. Scale the vectors, add them in any finite combination, and the result lies in their span. It is the smallest subspace that contains the set. Mathematicians speak of the span of a set and say that a vector lies in the span. The verb makes the stronger claim that this span fills a whole space.
- 12To generate an entire vector space by means of linear combinations of a given set of vectors.
The standard basis vectors span all of three-dimensional space.
The chosen wavelet functions span the space of signals the model needs to represent.
Similargenerate
Note
The verb turns the noun into a claim of completeness. To say a set spans a space is to say that every element of that space can be built as a finite linear combination of the set's members. It works in both active and passive forms: the vectors span the plane, or the plane is spanned by the vectors.
- 13A rope made fast at both ends so that a purchase can be hooked to the bight, or made fast at the center so that both ends can be used.
The mate rigged a span across the hatch and hooked the cargo tackle into its bight.
With the span made fast at its center, both free ends were used to steady the boom.
Note
Sailors' rigging turns the word into a physical object rather than a distance. One way to rig it is to make the rope fast at both ends, so that its slack middle, the bight, can take the hook of a purchase. Another is to make it fast at the center, so both ends stay free. A span in this sense is rigged and made fast; it is never measured.
- 14A pair of horses or other animals driven together, especially horses alike in color, form, and action.
The carriage rolled up behind a handsome span of matched bays.
He traded two cows for a span of oxen to break the new field.
Similarpair, team, yoke, brace
Note
A North American word with a root of its own. It probably comes from Old English ġespan, "a joining, a fastening together," and not from the word for the hand. A span is two animals driven as a single unit, and the word suggests a well-matched pair, alike in color, form and action, rather than any two that happen to share a harness. Oxen and mules can make a span too.
- 15The time required to execute a parallel algorithm on an unlimited number of processors, set by the longest chain of steps that must run one after another.
Adding more processors cannot push the running time below the algorithm's span.
Engineers reduced the span of the computation so it scaled better across the cluster.
Similardepth
Note
A parallel-computing measure that Ananya Kumar, Guy Blelloch and Robert Harper note is also called depth, or dependence depth (2017). It counts the steps that must happen one after another, however many processors are available, so it sets a floor on running time. Dividing an algorithm's total work by its span gives the parallelism the algorithm offers, which is why programmers work to shorten it.
- 16To fetter or hobble an animal, especially a horse, by binding its legs to keep it from wandering.
The drovers would span the horses each evening before making camp.
She spanned the pony with a soft rope so it could graze without straying.
Similarhobble, fetter, shackle
Note
A verb for restraining animals, usually horses, though the climbing magazine Mountain in 1972 uses it of dogs: "We spanned the dogs high up a corrie to the south of the ridge." Like hobble, it takes the animal as its object and means keeping it from wandering. Do not confuse it with the horse-matching verb, which takes no object at all.
- 17Of horses or other driven animals, to be matched in color, form, and action.
These bays span perfectly; you could not tell one from the other at a trot.
The judge said the sorrels spanned better than any pair at the fair.
Similarmatch
Note
A dated American word from the days of driven pairs, and the verb that goes with a matched team of horses. It is intransitive, so the horses themselves do the spanning: a pair spans well, or spanned better than any other at the fair. You do not span the horses. In present-day writing, say they are well matched, and keep it apart from the hobbling sense, which ties a horse rather than pairing it.
- 18Past tense of spin.
The weather vane span wildly as the storm blew in.
So they went in to where Gudruda sat spinning in the hall, singing as she span.
1891, H[enry] Rider Haggard, “How Hall of Lithdale Took Tidings to Iceland”Note
A different word that happens to share the spelling. This is the old strong past of spin, on the pattern of sing and sang, descended from the Germanic past form of the verb for spinning. A rhyme of 1593 pictures Adam delving while Eve span, and Rider Haggard still writes "singing as she span" in 1891. Modern standard English uses spun, yet span still surfaces: a 2014 Reuters report describes a truck that "span out of control."
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Practice
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Origins
From Middle English spanne, from Old English spann, from Proto-Germanic *spannō ("span, handbreadth"), tracing back to a Proto-Indo-European root *(s)pend- ("to stretch"). It is related to Dutch span and German Spanne. The sense "pair of horses" probably comes instead from Old English ġespan, ġespann ("a joining, fastening, clasp, yoke").
From Middle English spannen, from Old English spannan, from Proto-Germanic *spannaną ("to stretch, span"). It is related to German spannen and Dutch spannen.
From Middle English span, from Old English spann, the first and third person singular past tense of Proto-Germanic *spinnaną ("to spin").