ha

1 of 3

interjection

ˈhä 

variants or hah

—used especially to express surprise, joy, or triumph

ha

2 of 3

abbreviation (1)

hectare

HA

3 of 3

abbreviation (2)

1

hemagglutinin

Different circulating influenza A viruses are identified by referring to two signature proteins on their surfaces. One is hemagglutinin (HA), which has at least 15 known variants, or subtypes.

—Jeffery K. Taubenberger et al.

2

hour angle

Synonyms

Interjection

• hey
• hurrah
• hurray

Examples of ha in a Sentence

Interjection

ha! I was right all along!

Recent Examples on the Web

Interjection

There is no a-ha moment in that song. —Chris Willman, Variety, 3 Sep. 2025

Lotte Duty Free’s CEO, Kim Dong-ha, is actively strengthening the watches and jewelry category as both domestic and international customer demand for luxury watches and jewelry has boomed. —Kevin Rozario, Forbes.com, 27 Aug. 2025

This coastal project breached old defenses and realigned 7 km of embankment, creating ~183 ha of intertidal salt marsh. —Srishti Gupta, Interesting Engineering, 5 Aug. 2025

With like a honey packet squirted on top around the campfire, Paddy: ha. —Outside Online, 30 July 2025

Word History

Etymology

Interjection

Middle English, from Old English

First Known Use

Interjection

before the 12th century, in the meaning defined above

Phrases Containing ha

• ha ha
• hoo-ha

Rhymes for ha

• aah
• ah
• ahh
• aw
• awe
• bah
• blah
• bra
• caw
• claw
• craw
• daw

Kids Definition

ha

interjection

variants or hah

ˈhä

—used to express surprise, joy, or victory

Medical Definition

HA

abbreviation

hemagglutinin

Seasonal strains … evade our immune systems after vaccination or previous infection by constantly changing the structure of their hemagglutinin (HA) surface protein.

—Charles J. Russell, The New England Journal of Medicine