The Collaborative International Dictionary of English v.0.48:

Bandeau \Ban*deau"\ (b[a^]n*d[=o]"; b[a^]n"d[=o]), n.; pl.
   Bandeaux (b[a^]n*d[=o]z"). [F.]
   A narrow band or fillet, as for the hair, part of a
   headdress, etc.
   [Webster 1913 Suppl.]

         Around the edge of this cap was a stiff bandeau of
         leather.                                 --Sir W.
                                                  Scott.
   [1913 Webster] Bandlet
   Bandelet

WordNet (r) 3.0 (2006):

bandeau
    n 1: an undergarment worn by women to support their breasts
         [syn: brassiere, bra, bandeau]

Moby Thesaurus II by Grady Ward, 1.0:

162 Moby Thesaurus words for "bandeau":
   achievement, advocate, alerion, alpenstock, animal charge, annulet,
   argent, arm, armorial bearings, armory, arms, athletic supporter,
   azure, back, backbone, backing, band, bar, bar sinister, baton,
   bearer, bearings, bend, bend sinister, billet, blazon, blazonry,
   bordure, bra, brace, bracer, bracket, brassiere, broad arrow,
   buttress, cadency mark, cane, canton, carrier, cervix, chaplet,
   charge, chevron, chief, coat of arms, cockatrice, coronet, corset,
   crescent, crest, crook, cross, cross moline, crown, crutch, device,
   difference, differencing, eagle, ermine, ermines, erminites,
   erminois, escutcheon, falcon, falsies, fess, fess point, field,
   file, fillet, flanch, fleur-de-lis, foundation garment, fret,
   fulcrum, fur, fusil, garland, girdle, griffin, gules, guy, guywire,
   gyron, hatchment, helmet, heraldic device, honor point, impalement,
   impaling, inescutcheon, jock, jockstrap, label, lion, lozenge,
   mainstay, maintainer, mantling, marshaling, martlet, mascle, mast,
   metal, motto, mullet, neck, nombril point, octofoil, or, ordinary,
   orle, pale, paly, pean, pheon, prop, purpure, quarter, quartering,
   reinforce, reinforcement, reinforcer, rest, resting place, ribbon,
   rigging, rose, sable, saltire, scutcheon, shield, shoulder, shroud,
   soutien-gorge, spine, spread eagle, sprit, staff, standing rigging,
   stave, stay, stick, stiffener, strengthener, stripe, subordinary,
   support, supporter, sustainer, tenne, tincture, torse, tressure,
   unicorn, upholder, vair, vert, walking stick, wreath, yale