The Collaborative International Dictionary of English v.0.48:

Felicitous \Fe*lic"i*tous\, a.
   Characterized by felicity; happy; prosperous; delightful;
   skillful; successful; happily applied or expressed;
   appropriate.
   [1913 Webster]

         Felicitous words and images.             --M. Arnold.
   -- Fe*lic"i*tous*ly, adv. -- Fe*lic"i*tous*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

felicitous
    adj 1: exhibiting an agreeably appropriate manner or style; "a
           felicitous speaker" [ant: infelicitous]
    2: marked by good fortune; "a felicitous life"; "a happy
       outcome" [syn: felicitous, happy]

Moby Thesaurus II by Grady Ward, 1.0:

132 Moby Thesaurus words for "felicitous":
   Ciceronian, Demosthenian, Demosthenic, Tullian, a propos, ad rem,
   adapted, advantageous, advisable, affable, agreeable, amiable,
   amicable, applicable, apposite, appropriate, apropos, apt,
   articulate, auspicious, becoming, befitting, blissful, cheerful,
   civil, comely, compatible, complaisant, congenial, congruous,
   convenient, convincing, cordial, correct, decent, decorous,
   desirable, dovetailing, dulcet, eloquent, en rapport, enjoyable,
   expedient, facund, fair, fair and pleasant, favorable, feasible,
   felicific, fine, fit, fitted, fitten, fitting, fortunate,
   fructuous, geared, genial, genteel, germane, glib, good, goodly,
   gracious, grateful, gratifying, happy, harmonious, heart-warming,
   honeyed, inspired, just, just right, likable, likely, lucky, meet,
   mellifluous, mellow, meshing, nice, on the button, opportune, pat,
   pertinent, pleasant, pleasing, pleasurable, pleasure-giving,
   pleasureful, politic, profitable, proper, propitious, providential,
   qualified, recommendable, relevant, rewarding, right, ripe,
   satisfying, seasonable, seemly, silver, silver-tongued, slick,
   smooth, smooth-spoken, smooth-tongued, sortable, spellbinding,
   suitable, suited, suiting, sweet, tailored, telling, timely,
   to be desired, to the point, to the purpose, urbane, useful,
   welcome, well-chosen, well-expressed, well-put, well-spoken,
   well-timed, wise, worthwhile