1.  reasonable(a = adj.all) sensible - showing reason or sound judgment; "a sensible choice"; "a sensible person"
Antonym: unreasonable
Derived forms noun reasonableness₅, noun reasonableness₂

2.  reasonable(s = adj.all) fair, fairish - not excessive or extreme; "a fairish income"; "reasonable prices"
Derived forms noun reasonableness₄, noun reasonableness₃

3.  reasonable(s = adj.all) sane - marked by sound judgment; "sane nuclear policy"
Derived form noun reasonableness₁

1.  Having the faculty of reason; endued with reason; rational; as, a reasonable being. [1913 Webster]

2.  Governed by reason; being under the influence of reason; thinking, speaking or acting rationally, or according to the dictates of reason; agreeable to reason; just; rational; as, the measure must satisfy all reasonable men. [1913 Webster]
"By indubitable certainty, I mean that which doth not admit of any reasonable cause of doubting." [1913 Webster]
"Men have no right to what is not reasonable." [1913 Webster]

3.  Not excessive or immoderate; within due limits; proper; as, a reasonable demand, amount, price. [1913 Webster]
"Let . . . all things be thought upon
That may, with reasonable swiftness, add
More feathers to our wings." [1913 Webster]

   Reasonably; tolerably. [1913 Webster]
"I have a reasonable good ear in music." [1913 Webster]

reasonable, adj.
1 having sound judgement; moderate; ready to listen to reason.
2 in accordance with reason; not absurd.
3 a within the limits of reason; not greatly less or more than might be expected. b inexpensive; not extortionate. c tolerable, fair.
4 archaic endowed with the faculty of reason.

Derivative:
reasonableness n. reasonably adv.

Etymology:
ME f. OF raisonable (as REASON) after L rationabilis

N  cheapness, low price, depreciation, bargain, good penny worth, snap, gratuity, free quarters, free seats, free admission, pass, free pass, free warren, give-away, freebee, run of one's teeth, nominal price, peppercorn rent, labor of love, drug in the market, deadhead, cheap, low, low priced, moderate, reasonable, inexpensive, unexpensive, well worth the money, worth the money, magnifique et pas cher, good at the price, cheap at the price, dirt cheap, dog cheap, cheap, cheap as dirt, cheap and nasty, catchpenny, discounted, half-price, depreciated, unsalable, gratuitous, gratis, free, for nothing, costless, expenseless, without charge, not charged, untaxed, scotfree, shotfree, rent-free, free of cost, free of expense, honorary, unbought, unpaid, for a mere song, for a song, at cost, at cost price, at prime cost, at a reduction, a bon marche.

N  moderation, lenity, temperateness, gentleness, sobriety, quiet, mental calmness, moderating, anaphrodisia, relaxation, remission, mitigation, tranquilization, assuagement, contemporation, pacification, measure, juste milieu, golden mean, ariston metron, moderator, lullaby, sedative, lenitive, demulcent, antispasmodic, carminative, laudanum, rose water, balm, poppy, opiate, anodyne, milk, opium, poppy or mandragora, wet blanket, palliative, moderate, lenient, gentle, mild, mellow, cool, sober, temperate, reasonable, measured, tempered, calm, unruffled, quiet, tranquil, still, slow, smooth, untroubled, tame, peaceful, peaceable, pacific, halcyon, unexciting, unirritating, soft, bland, oily, demulcent, lenitive, anodyne, hypnotic, sedative, antiorgastic, anaphrodisiac, mild as mother's milk, milk and water, moderately, gingerly, piano, under easy sail, at half speed, within bounds, within compass, in reason, est modue in rebus, pour oil on troubled waters.

N  right, what ought to be, what should be, fitness, summum jus, justice, equity, equitableness, propriety, fair play, impartiality, measure for measure, give and take, lex talionis, Astraea, Nemesis, Themis, scales of justice, evenhanded justice, karma, suum cuique, clear stage, fair field and no favor, level playing field, morals, law, honor, virtue, right, good, just, reasonable, fit, equal, equable, equatable, evenhanded, fair, legitimate, justifiable, rightful, as it should be, as it ought to be, lawful deserved, rightly, +a bon droit, au bon droit, in justice, in equity, in reason, without distinction of persons, without regard to persons, without respect to persons, upon even terms, Int, all right!, fair's fair, Dieu et mon droit, in equal scale weighing delight and dole, justitia cuum cuique distribuit, justitiae soror incorrupta fides, justitia virtutem regina, thrice is he armed that hath his quarrel just.

N  probability, likelihood, credibleness, likeliness, vraisemblance, verisimilitude, plausibility, color, semblance, show of, presumption, presumptive evidence, circumstantial evidence, credibility, reasonable chance, fair chance, good chance, favorable chance, reasonable prospect, fair prospect, good prospect, favorable prospect, prospect, wellgrounded hope, chance, probable, likely, hopeful, to be expected, in a fair way, plausible, specious, ostensible, colorable, ben trovato, well-founded, reasonable, credible, easy of belief, presumable, presumptive, apparent, probably, belike, in all probability, in all likelihood, very likely, most likely, like enough, odds on, odds in favor, ten to one, apparently, seemingly, according to every reasonable expectation, prim=a facie, to all appearance, the chances, the odds are, appearances are in favor of, chances are in favor of, there is reason to believe, there is reason to think, there is reason to expect, I dare say, all Lombard Street to a China orange.

N  intelligence, wisdom, intelligence, capacity, comprehension, understanding, cuteness, sabe, savvy, intellect, nous, parts, sagacity, mother wit, wit, esprit, gumption, quick parts, grasp of intellect, acuteness, acumen, subtlety, penetration, perspicacy, perspicacity, discernment, due sense of, good judgment, discrimination, cunning, refinement, head, brains, headpiece, upper story, long head, eagle eye, eagle- glance, eye of a lynx, eye of a hawk, wisdom, sapience, sense, good sense, common sense, horse sense, plain sense, rationality, reason, reasonableness, judgment, solidity, depth, profundity, caliber, enlarged views, reach of thought, compass of thought, enlargement of mind, genius, inspiration, geist, fire of genius, heaven-born genius, soul, talent, prudence, vigilance, tact, foresight, sobriety, self-possession, aplomb, ballast, a bright thought, not a bad idea, Solomon-like wisdom, intelligent, quick of apprehension, keen, acute, alive, brainy, awake, bright, quick, sharp, quick witted, keen witted, clear witted, sharp-eyed, sharp sighted, sharp witted, wide- awake, canny, shrewd, astute, clear-headed, farsighted, discerning, perspicacious, penetrating, piercing, argute, quick-witted, nimble-witted, needle-witted, sharp as a needle, sharp as a tack, alive to, clever, arch, pas si bete, acute, wise, sage, sapient, sagacious, reasonable, rational, sound, in one's right mind, sensible, abnormis sapiens, judicious, strong- minded, unprejudiced, unbiased, unbigoted, unprepossessed, undazzled, unperplexed, unwarped judgment, impartial, equitable, fair, cool, cool-headed, long-headed, hardheaded, strong-headed, long- sighted, calculating, thoughtful, reflecting, solid, deep, profound, oracular, heaven-directed, heaven-born, prudent, sober, stand, solid, considerate, politic, wise in one's generation, watchful, provident, in advance of one' age, wise as a serpent, wise as Solomon, wise as Solon, wise, sensible, reasonable, judicious, well- thought-out, well-planned, well-judged, well-advised, prudent, politic, expedient, aut regem aut fatuum nasci oportet, but with the morning cool reflection came, flosculi sententiarum, les affaires font les hommes, mas vale saber que haber, mas vale ser necio que profiadol nemo solus sapit, nosce te, gnothi seauton, nullum magnum ingenium sine mixtura dementiae fuit, sapere aude, victrix fortunae sapientia, intelligence, wisdom, intelligence, capacity, comprehension, understanding, cuteness, sabe, savvy, intellect, nous, parts, sagacity, mother wit, wit, esprit, gumption, quick parts, grasp of intellect, acuteness, acumen, subtlety, penetration, perspicacy, perspicacity, discernment, due sense of, good judgment, discrimination, cunning, refinement, head, brains, headpiece, upper story, long head, eagle eye, eagle- glance, eye of a lynx, eye of a hawk, wisdom, sapience, sense, good sense, common sense, horse sense, plain sense, rationality, reason, reasonableness, judgment, solidity, depth, profundity, caliber, enlarged views, reach of thought, compass of thought, enlargement of mind, genius, inspiration, geist, fire of genius, heaven-born genius, soul, talent, prudence, vigilance, tact, foresight, sobriety, self-possession, aplomb, ballast, a bright thought, not a bad idea, Solomon-like wisdom, intelligent, quick of apprehension, keen, acute, alive, brainy, awake, bright, quick, sharp, quick witted, keen witted, clear witted, sharp-eyed, sharp sighted, sharp witted, wide- awake, canny, shrewd, astute, clear-headed, farsighted, discerning, perspicacious, penetrating, piercing, argute, quick-witted, nimble-witted, needle-witted, sharp as a needle, sharp as a tack, alive to, clever, arch, pas si bete, acute, wise, sage, sapient, sagacious, reasonable, rational, sound, in one's right mind, sensible, abnormis sapiens, judicious, strong- minded, unprejudiced, unbiased, unbigoted, unprepossessed, undazzled, unperplexed, unwarped judgment, impartial, equitable, fair, cool, cool-headed, long-headed, hardheaded, strong-headed, long- sighted, calculating, thoughtful, reflecting, solid, deep, profound, oracular, heaven-directed, heaven-born, prudent, sober, stand, solid, considerate, politic, wise in one's generation, watchful, provident, in advance of one' age, wise as a serpent, wise as Solomon, wise as Solon, wise, sensible, reasonable, judicious, well- thought-out, well-planned, well-judged, well-advised, prudent, politic, expedient, aut regem aut fatuum nasci oportet, but with the morning cool reflection came, flosculi sententiarum, les affaires font les hommes, mas vale saber que haber, mas vale ser necio que profiadol nemo solus sapit, nosce te, gnothi seauton, nullum magnum ingenium sine mixtura dementiae fuit, sapere aude, victrix fortunae sapientia.

N  sanity, soundness, rationality, sobriety, lucidity, lucid interval, senses, sober senses, right mind, sound mind, mens sana, sane, rational, reasonable, compos mentis, of sound mind, sound, sound-minded, lucid, self-possessed, sober, sober-minded, in one's sober senses, in one's right mind, in possession of one's faculties, sanely.

reasonable care