Medical Definition of Sclereid
1. Type of sclerenchyma cell that differs from the fibre cell by not being greatly elongated. Often occurs singly (an idioblast) or in small groups, giving rise to a gritty texture in, for instance, the pear fruit, where it is known as a stone cell. May also occur in layers, for example in hard seed coats. This entry appears with permission from the Dictionary of Cell and Molecular Biology (11 Mar 2008)