plank

A plank is a long, flat piece of material, typically timber, but it can be metal, plastic, or composite. It is usually rectangular and thicker than a board. The term is used in construction, carpentry, flooring, and shipbuilding. Planks vary in thickness, width, and length depending on use, species, and building codes.

In construction and carpentry, planks serve as structural components, decking, scaffolding planks, and surfacing for floors or walls. Solid hardwood planks and engineered planks are common types; decking planks and formwork planks are other varieties. Wood species such as oak, pine, or maple are commonly used, but planks can also be made from metal or composite materials.

In fitness, the plank refers to an isometric exercise designed to strengthen the core and stabilizing muscles. Technique typically involves supporting the body on forearms or hands while maintaining a straight line from head to heels, with the abdomen engaged. Variations include the side plank and incline plank. Benefits commonly cited include improved core stability, posture, and endurance; proper form is important to prevent back strain.

Etymology and usage vary by region, but the core idea remains a flat, elongated piece or period of activity around a flat, rectangular unit. Planks of wood have been a basic building material for centuries, while the term has since expanded to describe related flooring products, structural components, and athletic exercises.