biceps

Etymology

It is borrowed from Latin biceps (“two-headed”),^[2][3][4][5] genitive bicipitis, which in classical Latin also described a mountain with two summits and in post-classical Latin, from 1533 or earlier, a muscle with two heads.^[2][6] Barnhart takes the English word as probably borrowed from French biceps (1562) as well as from Latin.^[6] The Latin adjective is formed from bi- (“two”) and -ceps, the combining form of caput (“head”),^[2][3][4][7] from Proto-Indo-European *kaput- (“head”).^[3][4] Weekley compares anceps (“doubtful”), from ambō and the same noun.^[8] The muscle was named for its structure, with two points of attachment.^[3][9]

Earliest recorded meaning

Having two heads: 1576, in William Lambarde's Perambulation of Kent.^[2] Etymonline dates the adjective to the 1630s,^[3] and Barnhart and Merriam-Webster date the word to 1634.^[6][7]

Semantic evolution

The general sense "two-headed", sometimes used of a mountain with two peaks, died out in the 19th century.^[2][10] In anatomy the adjective described muscles with two heads from 1597,^[2] and the noun named the large muscle at the front of the upper arm from 1615, in Helkiah Crooke's Mikrokosmographia, and the muscle at the back of the thigh from 1648.^[2] Etymonline dates the noun for the arm muscle to the 1640s.^[3] Because of its final -s the word has been reinterpreted as a plural, with a new singular bicep;^[2][9] the Oxford Dictionary of Word Origins finds examples from the 1970s,^[9] and Dictionary.com dates the back-formation to 1955–60.^[11]

Timeline

• 1576 – adjective, two-headed; also of a mountain, two-peaked (obsolete by 1838).^[2]
• 1597 – in anatomy, of a muscle: having two heads.^[2]
• 1615 – noun, the muscle at the front of the upper arm.^[2] Etymonline dates this noun to the 1640s.^[3]
• 1648 – the muscle at the back of the thigh.^[2]
• 1970s – the singular bicep.^[9]

Meanings

Noun

1. The large muscle at the front of the upper arm, which bends the forearm at the elbow: He flexed his biceps for the camera.^[12][7][2]
2. The large muscle at the back of the thigh, which bends the knee.^[7][2]
3. Any muscle with two heads or points of origin.^[12][7]

Adjective

1. (anatomy) Of a muscle: having two heads.^[2][10]
2. (obsolete, 1576–1838) Two-headed; of a mountain, having two peaks.^[2][10]

Related words

• bicipital
• triceps
• quadriceps
• capital
• chief
• head

Usage notes

The word is singular, with the plural biceps or, less often, bicepses.^[7] The singular bicep, made by taking the -s for a plural ending, is now common,^[2][9] although Etymonline notes that classicists reject it.^[3]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
5. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
6. ^ a b c Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
7. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
8. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
9. ^ a b c d e Cresswell, Julia (2021), Oxford Dictionary of Word Origins, 3rd ed., Oxford: Oxford University Press
10. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
11. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
12. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins