Hollywood's most memorable movie moments all have one thing in common-visually stunning costume design. Whether spectacular or subtle, elaborate or barely there, costumes must be more than merely a perfect fit; they speak a language all their own, communicating mood, personality, and setting, and propelling the action of the movie as much as a scripted line or synthetic clap of thunder. More than a few careers have been launched from costumes alone, and many an era defined by the intuition of a costume designer - think Charlie Chaplin in ''The Little Tramp'', Judy Garland in ''A Star Is Born'', Diane Keaton in ''Annie Hall'', Harrison Ford in ''Indiana Jones''. ''Dressed: A Century of Hollywood Costume Design'', is part glossy lookbook, part insightful guide to the costumer's art - and this exquisite collector's edition, the one book no film and fashion lover will want to be without.