[syn: attendant, consequent, accompanying, concomitant, incidental, ensuant, resultant, sequent]
The Collaborative International Dictionary of English v.0.48:
Incidental \In`ci*den"tal\, n.
   An incident; that which is incidental; esp., in the plural,
   an aggregate of subordinate or incidental items not
   particularized; as, the expense of tuition and incidentals.
   --Pope.
   [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Incidental \In`ci*den"tal\, a.
   Happening, as an occasional event, without regularity; coming
   without design; casual; accidental; hence, not of prime
   concern; subordinate; collateral; as, an incidental
   conversation; an incidental occurrence; incidental expenses.
   [1913 Webster]
         By some, religious duties . . . appear to be regarded .
         . . as an incidental business.           --Rogers.
   Syn: Accidental; casual; fortuitous; contingent; chance;
        collateral. See Accidental. -- In`ci*den"tal*ly,
        adv. -- In`ci*den"tal*ness, n.
        [1913 Webster]
              I treat either or incidentally of colors. --Boyle.
        [1913 Webster]
WordNet (r) 3.0 (2006):
incidental
    adj 1: (sometimes followed by `to') minor or casual or
           subordinate in significance or nature or occurring as a
           chance concomitant or consequence; "incidental expenses";
           "the road will bring other incidental advantages"; "extra
           duties incidental to the job"; "labor problems incidental
           to a rapid expansion"; "confusion incidental to a quick
           change" [syn: incidental, incident] [ant: basic]
    2: not of prime or central importance; "nonessential to the
       integral meanings of poetry"- Pubs.MLA [syn: incidental,
       nonessential]
    3: following or accompanying as a consequence; "an excessive
       growth of bureaucracy, with attendant problems"; "snags
       incidental to the changeover in management"; "attendant
       circumstances"; "the period of tension and consequent need
       for military preparedness"; "the ensuant response to his
       appeal"; "the resultant savings were considerable" [syn:
       attendant, consequent, accompanying, concomitant,
       incidental, ensuant, resultant, sequent]
    n 1: (frequently plural) an expense not budgeted or not
         specified; "he requested reimbursement of $7 for incidental
         expenses" [syn: incidental expense, incidental, minor
         expense]
    2: an item that is incidental
Moby Thesaurus II by Grady Ward, 1.0:
166 Moby Thesaurus words for "incidental":
   accessory, acciaccatura, accident, accidental, accompanying,
   addendum, addition, additional, adjunct, ado, adrift, adscititious,
   adventitious, afloat, afoot, aleatory, ancillary, appendage,
   appoggiatura, appurtenance, appurtenant, arabesque, article,
   ascititious, aspect, auxiliary, beside the mark, beside the point,
   beside the question, by-the-way, cadence, cadenza, case, casual,
   causeless, chance, chancy, circumstantial, collateral, coloratura,
   conditional, contingency, contingent, count, current, datum,
   destinal, detail, dicey, division, doing, element, embellishment,
   eventuating, extra, extraneous, extrinsic, facet, fact, factor,
   fatal, fatidic, fioritura, flight, flourish, fluky, fortuitous,
   going on, grace, grace note, haphazard, happening, happenstance,
   iffy, immaterial, impertinent, in hand, in the wind, inadmissible,
   inapplicable, inapposite, inappropriate, incidental note,
   inconsequent, inconsequential, indeterminate, inessential,
   insignificant, instance, irrelative, irrelevant, item, lesser,
   long mordent, matter, mere chance, minor, minor detail, minutia,
   minutiae, mordent, negligible, nihil ad rem, nonessential,
   not at issue, not-self, occasional, occurring, odd, off,
   off the subject, on, on foot, ongoing, ornament, other,
   out-of-the-way, paltry, parenthetical, part-time, particular,
   passage, passing, petty, point, pralltriller, prevailing,
   prevalent, provisional, random, regard, respect, resultant, risky,
   roulade, run, secondary, serendipitous, side, single mordent,
   spare, subordinate, subsidiary, superadded, superaddition,
   superfluous, supervenient, supplement, supplemental, supplementary,
   taking place, thing, trifling, trivial, turn, uncaused, under way,
   undetermined, unessential, unexpected, unforeseeable, unforeseen,
   unimportant, unlooked-for, unplanned, unpredictable