Hepatitis, a gastroenterological disease

Hydroelectric power

Hydroelectric Power is a source of power

High-energy physics

Head end power, a method for providing electricity to train carriages

High Explosive Plastic anti-tank ammunition, also called high explosive squash head (HESH)

Hep, a synonym for hip (slang)

Heterogeneous Element Processor, a type of supercomputer

Healthy eating pyramid

Housing equity partnership

Homotopy extension property, a property in algebraic topology.

Hotel Electric Power Electricity generated and used aboard a ship for general purposes.

A war cry of the Crusaders: originated as short for Hierosolyma est perdita (Latin for "Jerusalem is lost").

The Hep-Hep riots - a series of antisemitic riots in Germany and neighbouring countries in 1819.