peek-a-boo \¦ ̷ ̷ ̷ ̷ ˌ ̷ ̷ \adjective 1.: of, relating to, or being a document retrieval system in which desired documents are identified by light shining through matching holes in index cards 2.: offering only limited display or disclosure especially of a teasing sort < engages in some playful peek-a-boo nudity — Joe Leydon > < peek-a-boo publicity >