Tissue layer is a term used to describe the layers of cells that form the outermost layer of an organism. The three crossword solutions for this term are PLY (3 letters), MEMBRANE (8 letters), and TELA (4 letters). PLY refers to a thin layer of material, such as paper or fabric, made up of multiple layers of the same material. MEMBRANE is a thin layer of tissue that separates two areas or substances, such as the cell MEMBRANE. Finally, TELA is a type of tissue layer found in plants that consists of a single layer of cells.