Etymologically

complementum

Etymology and origin of the Latin word complementum

Confidence
Established
Formation
Derivation
First attested
81–43 BC, Cicero
Ultimate origin
Latin compleō
Etymology tree
inherited borrowed derived
Latin pleo
Latin compleo
Latin complementum
English complement

Forms

complēmentum n (genitive complēmentī); second declension[1]

Etymology

It is from Latin compleō (“to fill up”) + -mentum.[2][3][1]

Earliest recorded meaning

Cicero (81–43 BC), in the Orator, speaks of empty words stuffed into a sentence as fillers of the rhythm, quasi complēmenta numerōrum.[3][4][5]

Semantic evolution

Tacitus writes that the charge of treason was then the finishing touch of every accusation, and a law of 374 in the Theodosian Code uses it of the completion of an accusation.[3][4] Later writers use it for whatever completes something: Firmicus Maternus of the moon's fullness, Vegetius of the completion of a work, Augustine of Pentecost as the mystical completion of Easter;[3] Apringius, commenting on the Apocalypse, of the end of the Greek alphabet.[3] It also came to mean the act of completing or accomplishing, as in Isidore.[3]

In Medieval Latin it also meant the settlement of a debt and the carrying out of a punishment,[6] and scholastic writers in Britain used it for completeness, the full realisation of a being.[7] English complement (late 14th century) comes from it through Old French, and so, by another route, does compliment.[8]

Timeline

  • 81–43 BC – Cicero: words that only fill out the rhythm.[3][5]
  • 98–115 AD – Tacitus: treason as the finishing touch of all accusations.[3][5]
  • 343/350 AD – Firmicus Maternus, of the waxing moon.[3][5]
  • 354–430 AD – Augustine: Pentecost completes Easter.[3][5]
  • c. 560–636 AD – Isidore uses it for the fulfilling of commandments.[3][5]
  • late 14th century – English borrows complement through Old French.[8]

Meanings

Noun

  1. That which fills up or completes something, a complement.[2][4][3]
  2. (Late Latin) completion, fulfilment, accomplishment.[3][6][7]
  3. (Medieval Latin) The settlement of a debt; the carrying out of a punishment.[6]
  4. (Medieval Latin, philosophy) Completeness, full realisation.[7]

Word family

  • complēmentārius

Usage notes

Döderlein distinguishes it from supplēmentum: a complēmentum completes and crowns the whole, like a keystone, while a supplementum fills gaps and supplies what is missing.[9]

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b Glare, P. G. W., ed. (2012), Oxford Latin Dictionary, 2nd ed., Oxford: Oxford University Press
  3. ^ a b c d e f g h i j k l m Thesaurus linguae Latinae (1900–), Leipzig: Teubner; Berlin: De Gruyter; open-access ed., Munich: Bayerische Akademie der Wissenschaften
  4. ^ a b c Lewis, Charlton T.; Short, Charles (1879), A Latin Dictionary, Oxford: Clarendon Press
  5. ^ a b c d e f Köbler, Gerhard (2010), Lateinisches Abkunfts- und Wirkungswörterbuch für Altertum und Mittelalter, online ed., koeblergerhard.de
  6. ^ a b c Niermeyer, J. F. (1976), Mediae Latinitatis Lexicon Minus, Leiden: Brill
  7. ^ a b c Latham, R. E., D. R. Howlett, R. K. Ashdowne, et al. (1975–2013), Dictionary of Medieval Latin from British Sources, London: British Academy / Oxford University Press
  8. ^ a b Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  9. ^ Döderlein, Ludwig (1874), Döderlein’s Hand-book of Latin Synonymes, tr. H. H. Arnold, Andover: W. F. Draper

Borrowed into

Cite this entry

“Complementum.” Etymologically, 23 Oct. 2026, etymologically.com/la/complementum. Accessed 23 Oct. 2026.

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