Word.ws English Dictionary

sesquiannual

sesquiannual adjective: occurring once every one and a half years (i.e. once every 18 months).

Adjective

sesquiannual (not comparable)

  1. Occurring once every one and a half years (i.e. once every 18 months).
    • 1979, R. E. Meyer, Sesquiannual Report – April 1977-September 1978, Fossil Energy Division/DOE (DOE/W-7405-eng–26-1; cited in Surface Phenomena in Enhanced Oil Recovery (2013, →ISBN, page 718)
    • 1990, Sesquiannual Meeting of the American Society for Rickettsiology and Rickettsial Diseases; 8 (the society holds meetings roughly every 1.5 years, e.g. September 1989, May 1991, and September 1992)

Origin of sesquiannual

From sesqui- + annual.

Questions about sesquiannual

What does sesquiannual mean?
Sesquiannual means occurring once every one and a half years (i.e. once every 18 months).
What part of speech is sesquiannual?
Sesquiannual is an adjective.

Words near sesquiannual in the dictionary

  1. sesquialteran
  2. sesquialteras
  3. sesquialterate
  4. sesquialterous
  5. sesquialters
  6. sesquiannual
  7. sesquibasic
  8. sesquicarbonate
  9. sesquicarbonates
  10. sesquicentenarian
  11. sesquicentenarians

Source and license

Adapted from Wiktionary: sesquiannual (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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