Retro means objects and style that are related to the past and seem no longer modern or ‘up to date’. It means modes, motifs, music, art, techniques, fashion and materials that were used in the past.
Retro is the fashion of the by gone times but retro style refers to the new things that have some hints of the by gone times. For eg. if talking about the Victorian style furniture, excess use of ornaments was done in that era. That era mixed two or more styles and was predominantly noticed in furniture, fittings and decoration. If this fashion comes into style, it will be considered a retro comeback.