Describing the period of the American film industry (based in Hollywood, California) lasting roughly from 1920-1960, usually regarded as a time of great glamour and associated with stars like Audrey Hepburn and Elizabeth Taylor. The term is often used to refer to fashions that reflect those of that era. Casablanca and Gone with the Wind are two very famous Old Hollywood films. I'm not surprised she went with a glitzy Old Hollywood look tonight—it really suited her perfectly.