The U.S. Hearing Aid Compatibility Act, 1988

Acetic acid, often abbreviated HAc or HOAc

Honourable Artillery Company

Hyles-Anderson College

High-availability cluster (computing)

Acetaldehyde, often abbreviated HAc

Le Havre Athletic Club a professional football club in France.

Humanist Association of Canada

Hokkaido Air System Co., Ltd.

Human artificial chromosome

A hectare (symbol ha, pronounced /ˌhɛkˈtɛə(ɹ)/) is a unit of area equal to 10,000 square metres, or one square hectometre, and commonly used for measuring land area. A 100 m square is one ha. Its base unit, the are, was defined...

Hellenic Alternative Charts

Herefordshire Aero Club

Heavy Assault Cruiser, a spaceship category in the MMOG EVE Online (see Spaceships of EVE Online)

Hackney Downs railway station, London; National Rail station code HAC

Humboldt Arts Council - art council in California, USA.

Hóquei Académico de Cambra, a rink hockey club from Vale de Cambra, Portugal.

HHC (in the U.S. Army, meaning Headquarters and Headquarters Company) sometimes probounced "Hac"