Haiti (FIPS 10-4 country code)

the Hartmann number, in physics

A headache (cephalalgia in medical terminology) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. It ranks amongst the most common local pain complaints. The vast majority of headaches are...

Hells Angels, a motorcycle club

homeowners association

Hawaiian Airlines (IATA airline designator)

the British Rail pre-TOPS classification for twenty-four electric locomotives, later known as British Rail Class 71

Hyaluronan (also called hyaluronic acid or hyaluronate) is a non-sulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is one of the chief components of the extracellular matrix, contributes...

the ISO 639 alpha-2 language code for the Hausa language

the Highways Agency is an executive agency, part of the Department for Transport in the United Kingdom

home automation

Hearst-Argyle, a media company in the United States

Hāʼ, a letter of Arabic alphabet (ﻩ)

Ha, Bhutan

housing association

Head Automatica

Hydroxyapatite summary and related information.

the Ha! comedy channel, one of the precursors to Comedy Central

an interjection used to express joy, surprise, or laughter

"Ha", the lead single from Juvenile's album 400 Degreez

Hong Kong Housing Authority

Hå, a municipality in Norway

HA postal area

Kha, a letter of Cyrillic alphabet

Ha (kana), romanisation of the Japanese kana は and ハ

Hospital Authority (Hong Kong)

Ha (mythology), a minor deity in Egyptian mythology

Ha (ethnic group), a people in Tanzania

hemagglutinin or hemagglutination assay, in virology

high availability, as in a high-availability cluster

the former symbol for chemical element 105, first called hahnium (Ha), later given the systematic name, unnilpentium, and now called dubnium (Db)

a common prefix in Hebrew indicating the definite article.

hectare (ha), unit of surface area. 1 hectare = 10 000 m²