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Eta (letter), of the Greek alphabet (Η, η)

Eta Aircraft eta, a very high performance German glider

Burakumin, a Japanese social minority group (Eta is an old, derogatory name)

Eta reduction in mathematics, see lambda calculus

Estimated time of arrival

ETA (), a Basque paramilitary organisation

E.T.A., an independent film currently in production

ETA (band), a Swedish hardcore punk band

ETA movement, a watch movement

ETA programming language

ETA Systems, defunct manufacturer of ETA10 supercomputers

Electronic Technician's Association

Electronic Travel Authority, Australian electronic visa

Environmental Transport Association, a UK motor car breakdown and rescue organisation

Estonian Broadcasting Agency (Eesti Teadete Agentuur)

Ethiopian Teachers' Association, a trade union centre for Ethiopia

Ethiopian Telecommunication Agency

Evangelical Theological Association, an associated teaching institute of the Melbourne College of Divinity

Eidiko Tmima Alexiptotiston, Greek special operations unit