[1] : The Collaborative International Dictionary of English v.0.48

extra- \ex"tra-\ l., fr. exter. see exterior.
   a latin preposition, denoting beyond, outside of; -- often
   used in composition as a prefix signifying outside of,
   beyond, besides, or in addition to what is denoted by the
   word to which it is prefixed.
   1913 webster
see also:
exterior 

[2] : The Collaborative International Dictionary of English v.0.48

extra \ex"tra\, a.
   beyond what is due, usual, expected, or necessary;
   additional; supernumerary; also, extraordinarily good;
   superior; as, extra work; extra pay. "by working extra
   hours." --h. spencer.
   1913 webster

[3] : The Collaborative International Dictionary of English v.0.48

extra \ex"tra\, n.; pl. extras.
   1. something in addition to what is due, expected, or
      customary; esp., an added charge or fee, or something for
      which an additional charge is made; as, at some hotels air
      conditioning is an extra.
      webster 1913 suppl.

   2. an edition of a newspaper issued at a time other than the
      regular one.
      webster 1913 suppl.

   3. cricket a run, as from a bye, credited to the general
      score but not made from a hit.
      webster 1913 suppl.

   4. something of an extra quality or grade.
      webster 1913 suppl.
see also:
extras 

[4] : WordNet (r) 2.0

extra
     adj 1: further or added; "called for additional troops"; "need
            extra help"; "an extra pair of shoes"; "i have no
            other shoes"; "there are other possibilities" syn: othera,
             additional
     2: more than is needed, desired, or required; "trying to lose
        excess weight"; "found some extra change lying on the
        dresser"; "yet another book on heraldry might be thought
        redundant"; "skills made redundant by technological
        advance"; "sleeping in the spare room"; "supernumerary
        ornamentation"; "it was supererogatory of her to gloat";
        "delete superfluous or unnecessary words"; "extra ribs
        as well as other supernumerary internal parts"; "surplus
        cheese distributed to the needy" syn: excess, redundant,
         spare, supererogatory, superfluous, supernumerary,
         surplus
     3: added to a regular schedule; "a special holiday flight";
        "put on special buses for the big game" syn: special
     n 1: a minor actor in crowd scenes syn: supernumerary, spear
          carrier
     2: an additional edition of a newspaper usually to report a
        crisis
     3: something additional of the same kind; "he always carried
        extras in case of an emergency" syn: duplicate
     adv : unusually or exceptionally; "an extra fast car"
see also:
othera additional excess redundant spare supererogatory 
superfluous supernumerary surplus special spear carrier 
duplicate 

[5] : Moby Thesaurus II by Grady Ward, 1.0

213 moby thesaurus words for "extra":
   above, accessory, accident, accidental, added, addendum, addition,
   additional, additionally, adjunct, adscititious, adventitious,
   again, all included, also, altogether, amazingly,
   among other things, ancillary, and all, and also, and so, another,
   appendage, appurtenance, appurtenant, as a bonus, as well,
   ascititious, au reste, auxiliary, balance, beside, besides, beyond,
   bit player, bonus, casual, circumstantial, collateral,
   considerably, contingency, contingent, contributory, daily,
   daily newspaper, de trop, decoration, dividend, else, en plus,
   especially, exceptionally, excess, extra added attraction,
   extra dash, extra edition, extraordinarily, extremely, farther,
   figurant, figurante, filigree, filling, fillip, flourish,
   for lagniappe, fortuitous, fresh, frill, further, furthermore,
   gazette, gratuity, happenstance, held back, held in reserve,
   held out, in abeyance, in addition, in hand, incidental,
   inessential, inter alia, into the bargain, item, kicker, lagniappe,
   leftover, likewise, margin, markedly, mere chance, mint, more,
   moreover, mute, national newspaper, neighborhood newspaper, new,
   news, newspaper, newspaper of record, nonessential, not-self,
   notably, noticeably, occasional, odd, off, on the side, on top of,
   original, ornament, other, out-of-the-way, over, over and above,
   overage, overmeasure, overplus, overrun, overset, overstock,
   oversupply, padding, paper, part-time, particularly, plus,
   pourboire, premium, pristine, put aside, put by, rag, rarely,
   remainder, remaining, remarkably, reserve, saved, secondary, sheet,
   side, similarly, something extra, spare, spear-carrier, special,
   special edition, stand-in, standby, stored, strikingly, stuffing,
   subsidiary, substitute, supe, super, superadded, superaddition,
   superfluous, supernumerary, supervenient, supplement, supplemental,
   supplementary, support, supporting actor, supporting cast,
   surcharge, surplus, surplusage, surprisingly, suspended, tabloid,
   then, therewith, tip, to boot, to spare, too, trimming, twist,
   ulterior, unapplied, unbeaten, uncommon, uncommonly, unconsumed,
   understudy, unemployed, unessential, unexercised, unexpectedly,
   unexpended, unhandled, unspent, untapped, untouched, untrodden,
   unused, unusually, unutilized, very, waived, walk-on,
   walking gentleman, weekly, weekly newspaper, wrinkle, yet

[6] : Virtual Entity of Relevant Acronyms (Version 1.9, June 2002)

extra
     executiontrace analyser ibm, os/2
     
     

[7] : The Free On-line Dictionary of Computing (27 SEP 03)

extra
     
        object-oriented, pascal style, handles sets.  "a data model
        and query language for exodus", m.j. carey et al, sigmod 88
        conf proc, pp.413- 423, acm sigmod record 17:3 sept 1988.
     
     

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