Hierarchy pertains to a logical structure that uses ordered levels as a means of organizing data. A hierarchy can be used to define data aggregation.

heat pipe is described as a device that can quickly transfer heat from one point to another. Superconductor of heat is what it is often referred to, as it possess an extraordinary heat transfer capacity and rate with almost no heat loss.

Heat treatment is characterized as a combination of heating and cooling operations applied to a metal or alloy in the solid state to obtain desired conditions or properties.

Harp is described as one of the largest of all string instruments. It is musical instrument consisting of a triangular frame furnished with strings and sometimes with pedals, held upright, and played with the fingers.

Housing is described as structures collectively; structures in which people are housed, living accomodation, dwelling units.

High learning products are identified as items that require education or instruction before being able to operate, an example would be a computer.

Hood is a generic term for a device designed to capture contaminated air and conduct it into an exhaust duct system.