biennial

Etymology

It is from Latin biennium (“a period of two years”), or biennis (“lasting two years”), with the suffix -al;^{[2][3][4][5][6]} the Latin words are formed from bi- (“two”) and annus (“year”), the source of annual.^[6][2][7] Klein explains the vowel of the second element by a Latin sound law that turned an original short a into e in the closed, unaccented root syllable of the second element of a compound.^[6][7] Barnhart allows that it may also have been borrowed from French biennal, recorded in 1550.^[8][9]

Earliest recorded meaning

Lasting for two years: 1621 according to Barnhart and the 1620s in Etymonline;^[9][6] the OED's first quotation, from J. Howell's Epistolæ Ho-elianæ, is from 1645.^[2] Merriam-Webster Unabridged dates its sense "occurring every two years" to 1562.^[5]

Semantic evolution

The botanical use, of a plant that lives for two years, appears in 1691 in J. Ray's Wisdom of God.^[2] Johnson (1755) gave only the sense "of the continuance of two years", quoting Ray on plants that are "annual or biennial".^[10] The sense "happening every second year" is recorded from 1750, in Johnson's Rambler.^[2][6] The noun, a plant that grows in its first year and flowers, fruits and dies in the second, is recorded from 1772 in the OED and by 1770 in Etymonline,^[2][6] and Merriam-Webster dates the noun to 1723.^[5] From 1853, chiefly in the United States, it also named an event held every two years, at first an examination at Yale,^[2] and today especially an exhibition.^[5][11]

Timeline

• 1621 – lasting two years.^[9] The OED's first quotation is from 1645.^[2]
• 1691 – of plants, living two years.^[2]
• 1750 – happening every second year.^[2][6]
• 1772 – noun, a biennial plant.^[2] Etymonline dates it by 1770.^[6]
• 1853 – noun, an event held every two years, at first a Yale examination.^[2]

Meanings

Adjective

1. Happening once every two years: The society holds a biennial congress in Vienna.^[11][5][12]
2. Lasting or living for two years.^[11][5][12]
3. Of a plant, needing two growing seasons to complete its life cycle, flowering, fruiting and dying in the second.^[12][5][11]

Noun

1. A biennial plant.^[11][12][5]
2. An event held every two years, especially an exhibition.^[11][5][12]

Word family

• biennially

Related words

• biennium
• biannual
• semiannual
• annual
• perennial
• triennial

Usage notes

Biennial, every two years, is easily confused with biannual, twice a year, and Collins and Merriam-Webster contrast the two.^[11][5] Merriam-Webster also records biannual sometimes used to mean biennial.^[5] Random House notes that of the words for periods of time formed with bi-, only biennial is unambiguous, and advises semi- or "twice a" for the sense "twice each".^[13]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
4. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
5. ^ a b c d e f g h i j k Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
8. ^ Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
9. ^ a b c Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
10. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
11. ^ a b c d e f g Collins English Dictionary (2023), Glasgow: HarperCollins
12. ^ a b c d e The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
13. ^ Random House Webster's Unabridged Dictionary (1999), 2nd ed., New York: Random House