The Collaborative International Dictionary of English v.0.48:

frail \frail\, a. [Compar. frailer (fr[=a]l"[~e]r); superl.
   frailest.] [OE. frele, freile, OF. fraile, frele, F.
   fr[^e]le, fr. L. fragilis. See Fragile.]
   1. Easily broken; fragile; not firm or durable; liable to
      fail and perish; easily destroyed; not tenacious of life;
      weak; infirm.
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            That I may know how frail I am.       --Ps. xxxix.
                                                  4.
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            An old bent man, worn and frail.      --Lowell.
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   2. Tender. [Obs.]
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            Deep indignation and compassion frail. --Spenser.
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   3. Liable to fall from virtue or be led into sin; not strong
      against temptation; weak in resolution; also, unchaste; --
      often applied to fallen women.
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            Man is frail, and prone to evil.      --Jer. Taylor.
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The Collaborative International Dictionary of English v.0.48:

frail \frail\ (fr[=a]l), n. [OE. fraiel, fraile, OF. fraiel,
   freel, frael, fr. LL. fraellum.]
   A basket made of rushes, used chiefly for containing figs and
   raisins.
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   2. The quantity of raisins -- about thirty-two, fifty-six, or
      seventy-five pounds, -- contained in a frail.
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   3. A rush for weaving baskets. --Johnson.
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WordNet (r) 3.0 (2006):

frail
    adj 1: physically weak; "an invalid's frail body" [ant:
           robust]
    2: wanting in moral strength, courage, or will; having the
       attributes of man as opposed to e.g. divine beings; "I'm only
       a fallible human"; "frail humanity" [syn: fallible,
       frail, imperfect, weak]
    3: easily broken or damaged or destroyed; "a kite too delicate
       to fly safely"; "fragile porcelain plates"; "fragile old
       bones"; "a frail craft" [syn: delicate, fragile, frail]
    n 1: the weight of a frail (basket) full of raisins or figs;
         between 50 and 75 pounds
    2: a basket for holding dried fruit (especially raisins or figs)

Moby Thesaurus II by Grady Ward, 1.0:

218 Moby Thesaurus words for "frail":
   Adamic, Adamite, Adamitic, abulic, afraid, ailing, airy,
   anthropocentric, anthropological, attenuate, attenuated,
   backsliding, boyish, breakable, brittle, brittle as glass,
   cachectic, capricious, carnal, changeable, cheap-jack, cobwebby,
   consumptive, corruptible, cowardly, crackable, crippled, crisp,
   crispy, crumbly, crushable, dainty, debilitated, deciduous,
   decrepit, delicate, delicately weak, diaphanous, diluted, drained,
   dying, earthy, effeminate, enervated, ephemeral, erring, ethereal,
   evanescent, exhausted, fading, failing, faint, fainthearted,
   fallen, feeble, feebleminded, fickle, fine, fine-drawn, finespun,
   finite, fissile, fleeting, fleshly, flimsy, flitting, fly-by-night,
   flying, foible, fracturable, fragile, frailty, frangible, friable,
   fugacious, fugitive, gauzy, gimcrack, gimcracky, girlish, gossamer,
   gossamery, gracile, healthless, hominal, homocentric, human,
   humanistic, ill, impermanent, impetuous, impulsive, impure,
   in poor health, inconstant, infirm, insubstantial, invalid,
   invertebrate, jerry, jerry-built, lacerable, lacy, languishing,
   lapsed, light, lightweight, man-centered, misty, momentary,
   moribund, mortal, mutable, namby-pamby, nondurable, nonpermanent,
   of easy virtue, only human, pale, papery, passing, pasteboardy,
   peaked, peaky, peccable, perishable, petty, phthisic, pliable,
   poorly, postlapsarian, prodigal, puny, rare, rarefied, recidivist,
   recidivistic, reduced, reduced in health, run-down, scissile,
   scrawny, shatterable, shattery, shivery, short-lived, sick, sickly,
   sissified, skinny, sleazy, slender, slenderish, slight,
   slight-made, slim, slimmish, slinky, small, spineless, splintery,
   subtle, svelte, sylphlike, tacky, tellurian, temporal, temporary,
   tenuous, thin, thin-bodied, thin-set, thin-spun, thinnish,
   threadlike, transient, transitive, transitory, unangelic, unchaste,
   unclean, undurable, unenduring, ungodly, ungood, unhealthy,
   unrighteous, unsaintly, unsound, unstable, unsubstantial,
   unvirtuous, unwell, vague, valetudinarian, valetudinary, vice,
   virtueless, volatile, vulnerable, wanton, wasp-waisted,
   wasting away, watered, watered-down, watery, wayward, weak,
   weak-kneed, weak-minded, weak-willed, weakened, weakly, willowy,
   wiredrawn, wispy, with low resistance, womanish