Oi
Oi or OI may refer to:

In biology
Grey-faced petrel, also known by its Māori name oi
Orthostatic intolerance, a disorder of the autonomic nervous system
Osteogenesis imperfecta, a group of genetic bone disorders

In business
Oi (telecommunications), the largest landline telephone company in Brazil
Operational intelligence, in business analytics
Organizational intelligence, in business manage

In linguistics
Oi (digraph), a Latin-script digraph
Oi (interjection), an interjection used to get someone's attention, or to express surprise or disapproval
Oi language, a Mon–Khmer dialect cluster of southern Laos
Gha, a letter (Ƣ ƣ) erroneously referred to by Unicode as "oi"

In music
Oi!, a subgenre of punk rock
"Oi!" (song), a 2002 hit song for British grime music crew More Fire Crew

Organisations
Oi! (Hong Kong), a visual arts organisation in Hong Kong
Oi (Indonesia), an Iwan Fals fanbase foundation in Indonesia
Oriental Institute (disambiguation)
Orphans International, a global charitable organization that benefits orphans and abandoned children

Other uses
Japanese cruiser Ōi
O-I, a Japanese tank design of the Second World War

See also
Ōi (disambiguation), a number of places in Japan and the name of a light cruiser launched in 1920
Aussie Aussie Aussie, Oi Oi Oi, an Australian chant
Oi Oi Oi (album), an album by Boys Noize
Oy (disambiguation)
Hoy (disambiguation)
All pages with titles beginning with Oi