Definition
The raised, smooth area on the outside of a piston between the ring grooves. The lands separate and support the piston rings, holding them in their proper positions as the piston moves up and down in the cylinder.
Plain English
The flat strips of metal on the outside of a piston that sit between the slots where the rings go. They hold the rings in place.
Context Anchor
Seen in piston inspection, piston ring installation, and engine wear or damage discussions.
Derivation
From the older general use of 'land' meaning a flat, raised surface left between cut grooves. The same idea is used in machining and gunsmithing (the lands between rifling grooves in a barrel). It helps here because it pictures exactly what the part is: the untouched ridge left between the cut-out ring grooves.
Why Pilots Care
Cracked, worn, or broken lands let the rings shift or break, which causes loss of compression, oil burning, and possible engine damage. During inspection, condition of the lands is a key indicator of piston health.
Intuition Check
Do not read land here as an airplane touching down. In this engine context, a land is a solid strip of metal on the piston.
Example Sentence 1
During cylinder inspection, the technician checked each piston for cracks in the ring lands.
Example Sentence 2
Excessive clearance on the piston lands can allow combustion gases to blow by the rings.