A lintel or header is a horizontal beam used in the construction of buildings. It usually supports the masonry above a window or door opening.

Lintels may be wood, stone, steel or reinforced or pre tensioned concrete

pre-fabricated, pre-tensioned concrete lintels spanning garage doors

The term Lintel is also used to describe a computing platform consisting of the Linux operating system running on CPUs which are compatible with the x86 instruction set defined by Intel for their microprocessors.