To be in want of; to have cause or occasion for; to lack; to require, as supply or relief. [1913 Webster]
" With another verb, need is used like an auxiliary, generally in a negative sentence expressing requirement or obligation, and in this use it undergoes no change of termination in the third person singular of the present tense. “And the lender need not fear he shall be injured.”" Anacharsis (Trans. ). [1913 Webster]
"Other creatures all day long
Rove idle, unemployed, and less need rest." [1913 Webster]

   To be wanted; to be necessary. Chaucer. [1913 Webster]
"When we have done it, we have done all that is in our power, and all that needs." [1913 Webster]

   Of necessity. See Needs. Chaucer. [1913 Webster]

need, v. & n.
--v.
1 tr. stand in want of; require (needs a new coat).
2 tr. (foll. by to + infin.; 3rd sing. present neg. or interrog. need without to) be under the necessity or obligation (it needs to be done carefully; he need not come; need you ask?).
3 intr. archaic be necessary.
--n.
1 a a want or requirement (my needs are few; the need for greater freedom). b a thing wanted (my greatest need is a car).
2 circumstances requiring some course of action; necessity (there is no need to worry; if need arise).
3 destitution; poverty.
4 a crisis; an emergency (failed them in their need).

Idiom:
at need in time of need. had need archaic ought to (had need remember). have need of require; want. have need to require to (has need to be warned). in need requiring help. in need of requiring. need not have did not need to (but did).

Etymology:
OE neodian, ned f. Gmc

N  requirement, need, wants, necessities, necessaries, necessaries of life, stress, exigency, pinch, sine qua non, matter of necessity, case of need, case of life or death, needfulness, essentiality, necessity, indispensability, urgency, requisition, run upon, demand, call for, charge, claim, command, injunction, mandate, order, precept, desideratum, want, Adj, required, requisite, needful, necessary, imperative, essential, indispensable, prerequisite, called for, in demand, in request, urgent, exigent, pressing, instant, crying, absorbing, in want of, destitute of, ex necessitate rei, of necessity, there is no time to lose, it cannot be spared, it cannot be dispensed with, mendacem memorem esse oportet, necessitas non habet legem, nec tecum possum trivere nec sine te.

VB  require, need, want, have occasion for, not be able to do without, not be able to dispense with, prerequire, render necessary, necessitate, create a, necessity for, call for, put in requisition, make a requisition, stand in need of, lack, desiderate, desire, be necessary Adj.

N  insufficiency, inadequacy, inadequateness, incompetence, deficiency, imperfection, shortcoming, paucity, stint, scantiness, none to spare, bare subsistence, scarcity, dearth, want, need, lack, poverty, exigency, inanition, starvation, famine, drought, dole, mite, pittance, short allowance, short commons, half rations, banyan day, emptiness, poorness, depletion, vacancy, flaccidity, ebb tide, low water, a beggarly account of empty boxes, indigence, insolvency, drain of resources, impoverish, stint, put on short allowance, do insufficiently, scotch the snake, Adj, insufficient, inadequate, too little, not enough, unequal to, incompetent, weighed in the balance and found wanting, perfunctory, deficient, wanting imperfect, ill-furnished, ill-provided, ill- stored, ill-off, slack, at a low ebb, empty, vacant, bare, short of, out of, destitute of, devoid of, bereft of, denuded of, dry, drained, unprovided, unsupplied, unfurnished, unreplenished, unfed, unstored, untreasured, empty-handed, meager, poor, thin, scrimp, sparing, spare, stinted, starved, starving, halfstarved, famine-stricken, famished, jejune, scant, scarce, not to be had, not to be had for love or money, not to be had at any price, scurvy, stingy, at the end of one's tether, without resources, in want, in debt, insufficiently, in default of, for want of, failing, semper avarus eget.

VB  be insufficient, not suffice, come short of, run dry, want, lack, need, require, caret, be in want, live from hand to mouth, render insufficient Adj, drain of resources, impoverish, stint, put on short allowance, do insufficiently, scotch the snake.

N  poverty, indigence, penury, pauperism, destitution, want, need, neediness, lack, necessity, privation, distress, difficulties, wolf at the door, bad circumstances, poor circumstances, need circumstances, embarrassed circumstances, reduced circumstances, straightened circumstances, slender means, narrow means, straits, hand to mouth existence, res angusta domi, low water, impecuniosity, beggary, mendicancy, mendicity, broken fortune, loss of fortune, insolvency, empty pocket, empty purse, light purse, beggarly account of empty boxes, poor man, pauper, mendicant, mumper, beggar, starveling, pauvre diable, fakir, schnorrer, homeless person, poor, indigent, poverty-stricken, badly off, poorly off, ill off, poor as a rat, poor as a church mouse, poor as a Job, fortuneless, dowerless, moneyless, penniless, unportioned, unmoneyed, impecunious, out of money, out of cash, short of money, short of cash, without a rap, not worth a rap, qui n'a pas le sou, out of pocket, hard up, out at elbows, out at heels, seedy, bare-footed, beggarly, beggared, destitute, fleeced, stripped, bereft, bereaved, reduced, homeless, in want, needy, necessitous, distressed, pinched, straitened, put to one's shifts, put to one's last shifts, unable to keep the wolf from the door, unable to make both ends meet, embarrassed, under hatches, involved, insolvent, in forma pauperis, zonam perdidit, a penniless lass wi' a lang pedigree, a pobreza no hay verguenza, he that is down can fall no lower, poca roba poco pensiero, steeped, in poverty to the very lips, the short and simple annals of the poor.

N  desire, wish, fancy, fantasy, want, need, exigency, mind, inclination, leaning, bent, animus, partiality, penchant, predilection, propensity, willingness, liking, love, fondness, relish, longing, hankering, inkling, solicitude, anxiety, yearning, coveting, aspiration, ambition, vaulting ambition, eagerness, zeal, ardor, empressement, breathless impatience, overanxiety, impetuosity, appetite, appetition, appetence, appetency, sharp appetite, keenness, hunger, stomach, twist, thirst, thirstiness, drouth, mouthwatering, itch, itching, prurience, cacoethes, cupidity, lust, concupiscence, edge of appetite, edge of hunger, torment of Tantalus, sweet tooth, lickerish tooth, itching palm, longing eye, wistful eye, sheep's eye, greed, voracity, passion, rage, furore, mania, manie, inextinguishable desire, dipsomania, kleptomania, lover, amateur, votary, devotee, aspirant, solicitant, candidate, applicant, supplicant, cormorant, desideratum, want, a consummation devoutly to be wished, attraction, magnet, allurement, fancy, temptation, seduction, fascination, prestige, height of one's ambition, idol, whim, whimsy, whimsey, maggot, hobby, hobby-horse, Fortunatus's cap, wishing cap, wishing stone, wishing well, desirous, desiring, inclined, partial to, fain, wishful, optative, anxious, wistful, curious, at a loss for, sedulous, solicitous, craving, hungry, sharp-set, peckish, ravening, with an empty stomach, esurient, lickerish, thirsty, athirst, parched with thirst, pinched with hunger, famished, dry, drouthy, hungry as a hunter, hungry as a hawk, hungry as a horse, hungry as a church mouse, hungry as a bear, greedy, unsatisfied, unsated, unslaked, unsaturated, eager, avid, keen, burning, fervent, ardent, agog, all agog, breathless, impatient, bent on, intent on, set on, bent upon, intent upon, set upon, mad after, enrage, rabid, dying for, devoured by desire, aspiring, ambitious, vaulting, skyaspiring, high-reaching, desirable, desired, in demand, pleasing, appetizing, appetible, tantalizing, wistfully, fain, Int, would that, would that it were!, O for!, esto perpetual, the wish being father to the thought, sua cuique voluptas, hoc erat in votis, the mouth watering, the fingers itching, aut Caesar aut nullus, Cassius has a lean and hungry look, hungry as the grave, I was born to other things, not what we wish but what we want, such joy ambition finds, the sea hath bounds but deep desire hath none, ubi mel ibi apes.

VB  desire, wish, wish for, be desirous, have a longing, hope, care for, affect, like, list, take to, cling to, take a fancy to, fancy, prefer, have an eye, have a mind to, find it in one's heart, have a fancy for, set one's eyes upon, cast a sheep's eye upon, look sweet upon, take into one's head, have at heart, be bent upon, set one's cap at, set one's heart upon, set one's mind upon, covet, want, miss, need, feel the want of, would fain have, would fain do, would be glad of, be hungry, have a good appetite, play a good knife and fork, hunger after, thirst after, crave after, lust after, itch after, hanker after, run mad after, raven for, die for, burn to, desiderate, sigh for, cry for, gape for, gasp for, pine for, pant for, languish for, yearn for, long, be on thorns for, hope for, aspire after, catch at, grasp at, jump at, woo, court, solicit, fish for, spell for, whistle for, put up for, ogle, cause desire, create desire, raise desire, excite desire, provoke desire, whet the appetite, appetize, titillate, allure, attract, take one's fancy, tempt, hold out temptation, hold out allurement, tantalize, make one's mouth water, faire venir l'eau a la bouche, gratify desire.