1. An organ, process, or part resembling a plate as one of the
bony concentric layers surrounding the haversian canals in bone
or one of the incremental layers of cementum laid down in a
tooth. 2. A thin sheetlike organic structure in the enamel of a
tooth extending inward from a surface crack. 2. A small
medicated disk prepared from gelatin and glycerin for use
especially in the eyes.