Submitted by György Chityil ... on Sat, 01/20/2018 - 00:48 Hierarchy: AdverbDescription: {{proscribed|colloquial}} Occurring every three years; triennially.Ngram: triannuallyNgram Text: triannuallySource: WiktionaryIssue: 0Wiktionary tag: proscribedNgram Count: 1