The Collaborative International Dictionary of English v.0.48:

easygoing \eas"y*go`ing\, easy-going
\eas"y-go`ing\([=e]z"[y^]*g[=o]`[i^]ng), a.
   1. Moving easily; hence, mild-tempered; relaxed and casual;
      ease-loving; inactive. Contrasted with tense. [WordNet
      sense 2]

   Syn: degage, easy-going, laid-back.
        [1913 Webster + WordNet 1.5]

   2. having a lax moral or disciplinary standard. [WordNet
      sense 1] strict

   Syn: lenient.
        [WordNet 1.5]

   3. unhurried; as, an easygoing pace. Opposite of hurried.
      [WordNet sense 3]

   Syn: easy, leisurely.
        [WordNet 1.5]

   4. unaggressive; as, his easygoing approach to business.
      Opposite of aggressive. [WordNet sense 4]

   Syn: low-pressure.
        [WordNet 1.5]

Moby Thesaurus II by Grady Ward, 1.0:

187 Moby Thesaurus words for "easygoing":
   Bohemian, Micawberish, accepting, affable, afoot and lighthearted,
   airy, apathetic, at ease, at large, at liberty, ataractic,
   backward, blase, breezy, carefree, careless, casual, clear,
   clement, collected, comfortable, common, compassionate, composed,
   content, contented, cordial, cursory, dallying, degage, delaying,
   detached, devil-may-care, dilatory, dillydallying, disengaged,
   disinterested, dispassionate, disregardant, disregardful, drony,
   easy, emancipated, eupeptic, euphoric, even-tempered, faineant,
   familiar, flexible, flippant, folksy, foot-dragging, footloose,
   footloose and fancy-free, forbearant, forbearing, forgetful,
   forgiving, free, free and easy, free as air, freeborn, freed,
   gentle, go-as-you-please, gracious, happy, haymish, heedless,
   homely, homey, humane, impotent, imprecise, in the clear,
   inattentive, inconsiderate, incurious, indifferent, indolent,
   inexcitable, informal, insouciant, irregular, lackadaisical,
   laggard, lagging, lax, lazy, lenient, liberated, lingering,
   listless, loitering, loose, low-pressure, mellow, merciful, mild,
   mindless, moderate, natural, negligent, nonchalant, oblivious,
   of good comfort, offhand, offhanded, on the loose, overindulgent,
   overpermissive, patient, perfunctory, permissive, placid, plain,
   pleased, pococurante, poised, procrastinating, procrastinative,
   procrastinatory, reckless, reconciled, regardless, relaxed,
   released, remiss, resigned, respectless, sans souci, satisfied,
   scot-free, self-possessed, serene, shuffling, simple, slack,
   slipshod, sloppy, slothful, slow, sluggish, sociable, soft,
   tactless, tender, thoughtless, tolerant, tranquil, turned-off,
   unaffected, unambitious, unanxious, unassuming, unattached,
   unceremonious, uncommitted, uncomplaining, unconcerned,
   unconstrained, unconventional, undemanding, undiplomatic,
   undiscriminating, unengaged, unfussy, unheedful, unheeding,
   uninhibited, uninterested, uninvolved, unmindful, unofficial,
   unprepared, unready, unrepining, unreserved, unrestrained,
   unsolicitous, unstudied, untactful, unthinking, weak, wishy-washy,
   without care, work-shy