The Collaborative International Dictionary of English v.0.48:

Task \Task\ (t[.a]sk), n. [OE. taske, OF. tasque, F. t[^a]che,
   for tasche, LL. tasca, taxa, fr. L. taxare to rate, appraise,
   estimate. See Tax, n. & v.]
   1. Labor or study imposed by another, often in a definite
      quantity or amount.
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            Ma task of servile toil.              --Milton.
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            Each morning sees some task begin,
            Each evening sees it close.           --Longfellow.
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   2. Business; employment; undertaking; labor.
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            His mental powers were equal to greater tasks.
                                                  --Atterbury.
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   To take to task. See under Take.
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   Syn: Work; labor; employment; business; toil; drudgery;
        study; lesson; stint.
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The Collaborative International Dictionary of English v.0.48:

Task \Task\, v. t. [imp. & p. p. Tasked; p. pr. & vb. n.
   Tasking.]
   1. To impose a task upon; to assign a definite amount of
      business, labor, or duty to.
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            There task thy maids, and exercise the loom.
                                                  --Dryden.
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   2. To oppress with severe or excessive burdens; to tax.
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   3. To charge; to tax, as with a fault.
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            Too impudent to task me with those errors. --Beau. &
                                                  Fl.
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WordNet (r) 3.0 (2006):

task
    n 1: any piece of work that is undertaken or attempted; "he
         prepared for great undertakings" [syn: undertaking,
         project, task, labor]
    2: a specific piece of work required to be done as a duty or for
       a specific fee; "estimates of the city's loss on that job
       ranged as high as a million dollars"; "the job of repairing
       the engine took several hours"; "the endless task of
       classifying the samples"; "the farmer's morning chores" [syn:
       job, task, chore]
    v 1: assign a task to; "I tasked him with looking after the
         children"
    2: use to the limit; "you are taxing my patience" [syn: tax,
       task]

Moby Thesaurus II by Grady Ward, 1.0:

234 Moby Thesaurus words for "task":
   accuse, affair, agency, agentship, allege, arraign, article,
   assignment, attempt, authority, authorization, blame, book, bother,
   brevet, bring accusation, bring charges, bring to book, burden,
   burden with, business, busy, busywork, call to account, calling,
   care, cargo, censure, chalk talk, chare, charge, chide, chore,
   cite, commission, commissioning, commitment, complain, consignment,
   contract, criticize, cure, deadweight, deal, delegated authority,
   delegation, demand, denounce, denunciate, deputation, devoir,
   devolution, devolvement, dirty work, discourse, disquisition,
   donkeywork, drive, drudgery, duty, effort, embassy, employment,
   empowerment, encumber, engagement, enjoin, enterprise, entrusting,
   entrustment, errand, exact, executorship, exequatur, exercise,
   exposition, factorship, fag, fasten on, fasten upon, fatigue,
   finger, fish to fry, freight, freight with, full power, function,
   grind, handiwork, handwork, hang something on, harangue, headache,
   homework, homily, impeach, imply, impose, impose on, impose upon,
   impute, indict, industry, inflict on, inflict upon, inform against,
   inform on, insinuate, instruction, job, job of work, jurisdiction,
   keep busy, labor, lade, lay, lay charges, lay on, lecture,
   lecture-demonstration, legation, lesson, levy, license, lick,
   lick of work, lieutenancy, load, lodge a complaint, lodge a plaint,
   lumber, make-work, mandate, manual labor, matters in hand,
   millstone, mission, moil, moral, moral lesson, morality,
   moralization, nuisance, object lesson, obligation, occupation,
   odd job, office, onus, operation, oppress, overdrive, overtask,
   overtax, overwork, pain, piece of work, pin on, place, plan,
   plenipotentiary power, power of attorney, power to act, preachment,
   prefer charges, press charges, procuration, program, project,
   proposition, province, proxy, purview, put, put down, put on,
   put on report, put upon, rat race, rebuke, recital, recitation,
   recriminate, regency, regentship, report, reprehend, reprimand,
   reproach, reprove, responsibility, saddle, saddle with, scold,
   scut work, sermon, service, set, set task, skull session, slavery,
   spadework, stint, strain, stroke, stroke of work, struggle,
   subject to, sweat, take to task, talk, taunt with, tax, teaching,
   things to do, tiresome work, toil, travail, treadmill, trouble,
   trust, trusteeship, twit, undertaking, upbraid, venture,
   vicarious authority, vocation, warrant, weigh, weight,
   weight down with, work, yoke with