The act of extending or the state of being extended; a stretching out; enlargement in breadth or continuation of length; increase; augmentation; expansion. [1913 Webster]
That property of a body by which it occupies a portion of space. [1913 Webster]
Capacity of a concept or general term to include a greater or smaller number of objects; -- correlative of intension. [1913 Webster]
"The law is that the intension of our knowledge is in the inverse ratio of its extension." [1913 Webster]

"The extension of [the term] plant is greater than that of geranium, because it includes more objects." [1913 Webster]
The operation of stretching a broken bone so as to bring the fragments into the same straight line. [1913 Webster]
The straightening of a limb, in distinction from flexion. [1913 Webster]
A written engagement on the part of a creditor, allowing a debtor further time to pay a debt. [1913 Webster]

Counter extension. (Surg.) See under Counter. -- Extension table, a table so constructed as to be readily extended or contracted in length.

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OXFORD DICTIONARY

extension, n.
1 the act or an instance of extending; the process of being extended.
2 prolongation; enlargement.
3 a part enlarging or added on to a main structure or building.
4 an additional part of anything.
5 a a subsidiary telephone on the same line as the main one. b its number.
6 a an additional period of time, esp. extending allowance for a project etc. b permission for the sale of alcoholic drinks until later than usual, granted to licensed premises on special occasions.
7 extramural instruction by a university or college (extension course).
8 extent, range.
9 Logic a group of things denoted by a term.

Derivative

extensional adj.

Etymology

ME f. LL extensio (as EXTEND)

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THESAURUS

extension

L, access, accession, accessory, accompaniment, accretion, accrual, accruement, accumulation, acreage, addenda, addendum, additament, addition, additive, additory, additum, adjunct, adjuvant, advance, affective meaning, aggrandizement, alternate, alternative school, ambit, ampliation, amplification, amplitude, annex, annexation, appanage, appendage, appendant, appendix, appreciation, appurtenance, appurtenant, area, arm, ascent, attachment, augment, augmentation, ballooning, bearing, bigness, blab school, bloating, block, boarding school, body, boom, boost, breadth, broadening, buildup, bulk, caliber, call box, capacity, central school, coda, coin telephone, coloring, coming after, compass, complement, comprehensiveness, concomitant, connotation, consecution, consecutiveness, consequence, consolidated school, continualness, continuance, continuation, continuation school, continuing, continuity, continuum, corollary, correspondence school, country day school, coverage, crescendo, dame school, day school, denotation, deployment, depth, descent, desk telephone, development, dial telephone, diameter, dimension, dimensions, dispersion, distance, distension, drawing out, drift, edema, effect, elevation, ell, elongation, emptiness, empty space, endurance, enlargement, essence, evening school, expanse, expansion, extensiveness, extent, extrapolation, fanning out, field, finishing school, fixture, flare, flood, following, force, free school, gain, galactic space, gauge, girth, gist, grammatical meaning, greatening, greatness, growth, gush, height, hike, hiking, idea, impact, implication, import, increase, increment, infinite space, infinity, inflation, informal school, intension, interstellar space, jump, largeness, leap, length, lengthening, lengthiness, lexical meaning, line, lineage, linear measures, lingering, literal meaning, logical sequence, long time, longitude, longness, magnification, magnitude, maintenance, mass, meaning, measure, measurement, mileage, mounting, mouthpiece, multiplication, night school, nongraded school, nothingness, offshoot, open classroom school, orbit, order, order of succession, outer space, overall length, overtone, pay station, pendant, pensionat, perpetuation, perpetuity, perseverance, persistence, pertinence, phone, pith, platoon school, point, posteriority, postposition, practical consequence, private school, procession, procrastination, production, productiveness, progress, progression, progressive school, proliferation, prolongation, proportion, proportions, protraction, public school, public telephone, purport, pursuance, purview, push-button telephone, radius, raise, raising, range, range of meaning, reach, real meaning, receiver, reference, referent, reinforcement, relation, relevance, repetition, rise, rotation, run, scale, school without walls, scope, semantic cluster, semantic field, sense, sequence, series, side effect, side issue, significance, signification, significatum, signifie, size, snowballing, space, span, span of meaning, spatial extension, special school, sphere, spirit, splay, spread, spreading, spreading out, staying power, storefront school, straight course, strain, street academy, stretch, stretching, stringing out, structural meaning, subjunction, substance, succession, successiveness, suffixation, sum, sum and substance, summer school, superficial extension, supplement, surface, surge, sustained action, sustenance, sweep, swelling, symbolic meaning, tailpiece, telephone, telephone booth, telephone engineering, telephone extension, telephone mechanics, telephone receiver, telephonics, telephony, tenor, tension, totality of associations, tract, transferred meaning, transmitter, tumescence, unadorned meaning, undergirding, undertone, uninterrupted course, union school, unremittingness, up, upping, upsurge, upswing, uptrend, upturn, vacation school, value, volume, wall telephone, waxing, way, widening, width, wing, yardage

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ROGET THESAURUS

extension

Copy

N copy, facsimile, counterpart, effigies, effigy, form, likeness, image, picture, photo, xerox, similitude, semblance, ectype, photo offset, electrotype, imitation, model, representation, adumbration, study, portrait, resemblance, duplicate, reproduction, cast, tracing, reflex, reflexion, reflection, shadow, echo, transcript, transcription, recording, scan, chip off the old block, reprint, new printing, rechauffe, apograph, fair copy, parody, caricature, burlesque, travesty, travestie, paraphrase, derivative, derivation, modification, expansion, extension, revision, second edition, servile copy, servile imitation, plagiarism, counterfeit, fake, pasticcio, faithful, lifelike, close, conscientious, unoriginal, imitative, derivative.

Increase

N increase, augmentation, enlargement, extension, dilatation, increment, accretion, accession, development, growth, aggrandizement, aggravation, rise, ascent, exaggeration exacerbation, spread, flood tide, gain, produce, product, profit, increased, on the increase, undiminished, additional, crescendo, vires acquirit eundo.

Space

N space, extension, extent, superficial extent, expanse, stretch, hyperspace, room, scope, range, field, way, expansion, compass, sweep, swing, spread, dimension, length, distance, size, volume, hypervolume, latitude, play, leeway, purchase, tolerance, room for maneuver, spare room, elbow room, house room, stowage, roomage, margin, opening, sphere, arena, open space, free space, void, waste, wildness, wilderness, moor, moorland, campagna, abyss, unlimited space, infinity, world, ubiquity, length and breadth of the land, proportions, acreage, acres, acres and perches, roods and perches, hectares, square miles, square inches, square yards, square centimeters, square meters, yards (clothing), ares, arpents, spacious, roomy, extensive, expansive, capacious, ample, widespread, vast, world-wide, uncircumscribed, boundless, shoreless, trackless, pathless, extended, extensively, wherever, everywhere, far and near, far and wide, right and left, all over, all the world over, throughout the world, throughout the length and breadth of the land, under the sun, in every quarter, in all quarters, in all lands, here there and everywhere, from pole to pole, from China to Peru, from Indus to the pole, from Dan to Beersheba, from end to end, on the face of the earth, in the wide world, from all points of the compass, to the four winds, to the uttermost parts of the earth.

Expansion

N expansion, increase of size, enlargement, extension, augmentation, amplification, ampliation, aggrandizement, spread, increment, growth, development, pullulation, swell, dilation, rarefaction, turgescence, turgidness, turgidity, dispansion, obesity, hydrocephalus, hydrophthalmus, dropsy, tumefaction, intumescence, swelling, tumor, diastole, distension, puffing, puffiness, inflation, pandiculation, dilatability, expansibility, germination, growth, upgrowth, accretion, budding, gemmation, overgrowth, overdistension, hypertrophy, tympany, bulb, plumper, superiority of size, big bang, Hubble constant, expanded larger, &c (large), swollen, expansive, wide open, wide spread, flabelliform, overgrown, exaggerated, bloated, fat, turgid, tumid, hypertrophied, dropsical, pot bellied, swag bellied, edematous, oedematous, obese, puffy, pursy, blowzy, bigswoln, distended, patulous, bulbous, full blown, full grown, full formed, big, abdominous, enchymatous, rhipidate, tumefacient, tumefying.

Length

N length, longitude, span, mileage, distance, line, bar, rule, stripe, streak, spoke, radius, lengthening, prolongation, production, protraction, tension, tensure, extension, line, nail, inch, hand, palm, foot, cubit, yard, ell, fathom, rood, pole, furlong, mile, league, chain, link, arpent, handbreadth, jornada, kos, vara, astronomical unit, AU, light- year, parsec, nanometer, nm, micron, micrometer, millimicron, millimeter, mm, centimeter, cm, meter, kilometer, km, pedometer, perambulator, scale, long, longsome, lengthy, wiredrawn, outstretched, lengthened, sesquipedalian, interminable, no end of, macrocolous, linear, lineal, longitudinal, oblong, as long as my arm, as long as today and tomorrow, unshortened &c (shorten), lengthwise, at length, longitudinally, endlong, along, tandem, in a line, in perspective, from end to end, from stem to stern, from head to foot, from the crown of the head to the sole of the foot, from top to toe, fore and aft.

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