The Collaborative International Dictionary of English v.0.48:

Troubadour \Trou"ba*dour`\, n. [F. troubadour, fr. Pr. trobador,
   (assumed) LL. tropator a singer, tropare to sing, fr. tropus
   a kind of singing, a melody, song, L. tropus a trope, a song,
   Gr. ? a turn, way, manner, particular mode in music, a trope.
   See Trope, and cf. Trouv?re.]
   One of a school of poets who flourished from the eleventh to
   the thirteenth century, principally in Provence, in the south
   of France, and also in the north of Italy. They invented, and
   especially cultivated, a kind of lyrical poetry characterized
   by intricacy of meter and rhyme, and usually of a romantic,
   amatory strain.
   [1913 Webster]

WordNet (r) 3.0 (2006):

troubadour
    n 1: a singer of folk songs [syn: folk singer, jongleur,
         minstrel, poet-singer, troubadour]

Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "troubadour":
   Ahasuerus, Ancient Mariner, Argonaut, Flying Dutchman, Goliard,
   Meistersinger, Odysseus, Oisin, Ossian, Parnassian, Ulysses,
   arch-poet, ballad maker, ballad singer, balladeer, balladist,
   balladmonger, bard, beat poet, bird of passage, bucoliast, drifter,
   elegist, epic poet, fili, floater, folk singer, folk-rock singer,
   gad, gadabout, gleeman, go-about, idyllist, imagist, itinerant,
   jongleur, laureate, librettist, major poet, maker, minnesinger,
   minor poet, minstrel, modernist, mover, occasional poet, odist,
   pastoral poet, pastoralist, peregrinator, peregrine, peripatetic,
   poet, poet laureate, poetress, rambler, rhapsode, rhapsodist,
   rhymer, rhymester, roamer, rolling stone, rover, runabout,
   satirist, scop, serenader, skald, sonneteer, straggler,
   street singer, stroller, strolling minstrel, strolling player,
   symbolist, trouveur, trovatore, vers libriste, vers-librist,
   visitant, wait, wanderer, wandering minstrel, wandering scholar