›to cover something with a layer of something else: Sticky tracing paper overlaid on street maps lets travelers chart their course again and again.overlay sth with sthBy mapping the entire retail landscape and overlaying it with demographic information, the company is able to isolate store-by-store effects of television ad campaigns.
›to add information, data, ideas, etc. to existing information: A computer model overlaid information about age, work experience, and educational attainment.