triennial
adjective
tri·en·ni·al (ˌ)trī-ˈe-nē-əl 
1
: occurring or being done every three years
the triennial convention
2
: consisting of or lasting for three years
a triennial contract
triennial noun
triennially
(ˌ)trī-ˈe-nē-ə-lē
adverb 
Example Sentences
Recent Examples on the Web Terrill’s work has been materializing in many places as of late: in the triennial exhibition organized by El Museo del Barrio in New York two years ago and in a small solo show at Park View / Paul Soto in L.A. early this spring. 
Los Angeles Times, 13 Aug. 2022 An African country alternates with China in hosting the triennial Forum of China Africa Cooperation, which the Chinese president traditionally attends and meets one-on-one with almost every head of state. Alan Crawford, Bloomberg.com, 5 Aug. 2022 More than 100 artists will be featured at dozens of Northeast Ohio venues as a part of this international triennial exhibition, first held in 2018. Annie Nickoloff, cleveland, 14 July 2022 The museum's triennial competition, now in its 16th year, says Bey, has become a force in the art world for expanding representation, giving emphasis to the portrayal of marginalized communities. Diane Bernard, Smithsonian Magazine, 12 July 2022 They will be awarded $25,000 in career-building stipends, plus money for research trips, and career-development services from triennial staff and partnering institutions. Steven Litt, cleveland, 3 July 2022 Since 2011, the W.S.C. has conducted a triennial survey of those members about container loss, and concluded, in 2020, that, on average, 1,382 containers go overboard each year. Kathryn Schulz, The New Yorker, 30 May 2022 The Outwin, the National Portrait Gallery’s triennial portrait show, gives us a galaxy of distinct American personalities. Brian T. Allen, National Review, 11 June 2022 The Summit of the Americas, a triennial gathering of regional leaders from Alaska to Patagonia that the US is hosting for the first time since 1994, is the Biden's administration strongest effort to push the US agenda in the Western Hemisphere. Stefano Pozzebon, CNN, 8 June 2022 See More
Los Angeles Times, 13 Aug. 2022 An African country alternates with China in hosting the triennial Forum of China Africa Cooperation, which the Chinese president traditionally attends and meets one-on-one with almost every head of state. Alan Crawford, Bloomberg.com, 5 Aug. 2022 More than 100 artists will be featured at dozens of Northeast Ohio venues as a part of this international triennial exhibition, first held in 2018. Annie Nickoloff, cleveland, 14 July 2022 The museum's triennial competition, now in its 16th year, says Bey, has become a force in the art world for expanding representation, giving emphasis to the portrayal of marginalized communities. Diane Bernard, Smithsonian Magazine, 12 July 2022 They will be awarded $25,000 in career-building stipends, plus money for research trips, and career-development services from triennial staff and partnering institutions. Steven Litt, cleveland, 3 July 2022 Since 2011, the W.S.C. has conducted a triennial survey of those members about container loss, and concluded, in 2020, that, on average, 1,382 containers go overboard each year. Kathryn Schulz, The New Yorker, 30 May 2022 The Outwin, the National Portrait Gallery’s triennial portrait show, gives us a galaxy of distinct American personalities. Brian T. Allen, National Review, 11 June 2022 The Summit of the Americas, a triennial gathering of regional leaders from Alaska to Patagonia that the US is hosting for the first time since 1994, is the Biden's administration strongest effort to push the US agenda in the Western Hemisphere. Stefano Pozzebon, CNN, 8 June 2022 See More Word History
First Known Use
1562, in the meaning defined at sense 1