The Collaborative International Dictionary of English v.0.48:

Robust \Ro*bust"\, a. [L. robustus oaken, hard, strong, fr.
   robur strength, a very hard kind of oak; cf. Skr. rabhas
   violence: cf. F. robuste.]
   1. Evincing strength; indicating vigorous health; strong;
      sinewy; muscular; vigorous; sound; as, a robust body;
      robust youth; robust health.
      [1913 Webster]

   2. Violent; rough; rude.
      [1913 Webster]

            While romp-loving miss
            Is hauled about in gallantry robust.  --Thomson.
      [1913 Webster]

   3. Requiring strength or vigor; as, robust employment.
      --Locke.
      [1913 Webster]

   Syn: Strong; lusty; sinewy; sturdy; muscular; hale; hearty;
        vigorous; forceful; sound.

   Usage: Robust, Strong. Robust means, literally, made of
          oak, and hence implies great compactness and toughness
          of muscle, connected with a thick-set frame and great
          powers of endurance. Strong denotes the power of
          exerting great physical force. The robust man can bear
          heat or cold, excess or privation, and toil on through
          every kind of hardship; the strong man can lift a
          great weight, can give a heavy blow, and a hard gripe.
          "Robust, tough sinews bred to toil." --Cowper.
          [1913 Webster]

                Then 'gan the villain wax so fierce and strong,
                That nothing may sustain his furious force.
                                                  --Spenser.
          [1913 Webster]

WordNet (r) 3.0 (2006):

robust
    adj 1: sturdy and strong in form, constitution, or construction;
           "a robust body"; "a robust perennial" [ant: frail]
    2: marked by richness and fullness of flavor; "a rich ruby
       port"; "full-bodied wines"; "a robust claret"; "the robust
       flavor of fresh-brewed coffee" [syn: full-bodied, racy,
       rich, robust]
    3: strong enough to withstand or overcome intellectual
       challenges or adversity; "the experiment yielded robust
       results"; "a robust faith"
    4: rough and crude; "a robust tale"

Moby Thesaurus II by Grady Ward, 1.0:

102 Moby Thesaurus words for "robust":
   able-bodied, active, acute, aggressive, animated, athletic, beefy,
   booming, bouncing, brawny, brisk, doughty, dynamic, energetic,
   enterprising, enthusiastic, fit, flavorful, flush, forceful,
   forcible, forcy, fruity, full of pep, full-blooded, full-bodied,
   full-strength, go-go, gutsy, gutty, hale, hale and hearty, hard,
   hard as nails, hardy, healthy, hearty, hefty, husky, impetuous,
   incisive, intense, iron-hard, keen, kinetic, lively, living, lusty,
   mettlesome, mighty, muscular, nervy, nutty, obstinate, peppy,
   potent, powerful, prospering, prosperous, puissant, pungent,
   red-blooded, rich, roaring, robustious, robustuous, rude, rugged,
   sapid, sinewy, smacking, snappy, sound, spanking, spirited,
   stalwart, staunch, steely, stout, strapping, strenuous, strong,
   strong as brandy, strong as strong, strong-willed, sturdy,
   take-charge, take-over, thrifty, thriving, tough, trenchant,
   vibrant, vigorous, vital, vivacious, vivid, well-knit, zestful,
   zesty, zip, zippy



The Jargon File (version 4.4.7, 29 Dec 2003):

robust
 adj.

    Said of a system that has demonstrated an ability to recover gracefully
    from the whole range of exceptional inputs and situations in a given
    environment. One step below bulletproof. Carries the additional
    connotation of elegance in addition to just careful attention to detail.
    Compare smart, oppose brittle.


The Free On-line Dictionary of Computing (30 December 2018):

robust

   Said of a system that has demonstrated an ability to recover
   gracefully from the whole range of exceptional inputs and
   situations in a given environment.  One step below
   bulletproof.  Carries the additional connotation of elegance
   in addition to just careful attention to detail.  Compare
   smart, opposite: brittle.

   [Jargon File]