complement

Etymology

From Middle English complement, from Latin complementum (“that which fills up or completes”), from compleō (“I fill up, I complete”) (English complete). Doublet of compliment.

noun

1. (now rare) Something (or someone) that completes; the consummation.
2. (obsolete) The act of completing something, or the fact of being complete; completion, completeness, fulfilment.
3. The totality, the full amount or number which completes something.
   Some 11 members of Somerton council's complement of 15 stepped down on Tuesday. 30 October 2009, The Guardian
4. (obsolete) Something which completes one's equipment, dress etc.; an accessory.
   A doleful case desires a doleful song, Without vain art or curious complements. 1591, Edmund Spenser, The Teares of the Muses [The Tears of the Muses]: Polyhymnia
5. (nautical) The whole working force of a vessel.
6. (heraldry) Fullness (of the moon).
   The sixth Bishop of Ely had very curious arms, for he bore both sun and moon on his shield, the sun "in his splendour" and the moon "in her complement". 1912, Allen Phoebe, Peeps at Heraldry, page 33
7. (astronomy, geometry) An angle which, together with a given angle, makes a right angle.
8. Something which completes, something which combines with something else to make up a complete whole; loosely, something perceived to be a harmonious or desirable partner or addition.
   History is the complement of poetry. 1854, James Stephen, On Desultory and Systematic Reading
   It would be too much to imagine that improving stations will alone create a much needed new image in the public eye; a smartly turned out station staff is a very necessary complement to a smart station. 1962 October, Brian Haresnape, “Focus on B.R. passenger stations”, in Modern Railways, page 255
   London's Kings Place, now one year old, established itself as a venue for imaginative programming, a complement to the evergreen Wigmore Hall. 13 December 2009, The Guardian
9. (grammar, linguistics) A word or group of words that completes a grammatical construction in the predicate and that describes or is identified with the subject or object.
   Why has our grammar broken down at this point? It is not difficult to see why. For, we have failed to make any provision for the fact that only some Verbs in English (i.e. Verbs like those italicized in (5) (a), traditionally called Transitive Verbs) subcategorize ( = ‘takeʼ) an immediately following NP Complement, whereas others (such as those italicised in (5) (b), traditionally referred to as Intransitive Verbs) do not. 1988, Andrew Radford, chapter 7, in Transformational grammar: a first course, Cambridge, UK: Cambridge University Press, page 340
10. (music) An interval which, together with the given interval, makes an octave.
11. (optics) The color which, when mixed with the given color, gives black (for mixing pigments) or white (for mixing light).
    The complement of blue is orange.
12. (set theory) Given two sets, the set containing one set's elements that are not members of the other set (whether a relative complement or an absolute complement).
    The complement of the odd numbers is the even numbers, relative to the natural numbers.
13. (immunology) One of several blood proteins that work with antibodies during an immune response.
14. (logic) An expression related to some other expression such that it is true under the same conditions that make other false, and vice versa.
15. (electronics) A voltage level with the opposite logical sense to the given one.
16. (computing) A bit with the opposite value to the given one; the logical complement of a number.
17. (computing, mathematics) The diminished radix complement of a number; the nines' complement of a decimal number; the ones' complement of a binary number.
    The complement of 01100101_2 is 10011010_2.
18. (computing, mathematics) The radix complement of a number; the two's complement of a binary number.
    The complement of 01100101_2 is 10011011_2.
19. (computing, mathematics) The numeric complement of a number.
    The complement of −123 is 123.
20. (genetics) A nucleotide sequence in which each base is replaced by the complementary base of the given sequence: adenine (A) by thymine (T) or uracil (U), cytosine (C) by guanine (G), and vice versa.
    A DNA molecule is formed from two strands, each of which is the complement of the other.
21. Obsolete spelling or misspelling of compliment.
22. (biochemistry) Synonym of alexin
23. (economics) Abbreviation of complementary good.

verb

1. To complete, to bring to perfection, to make whole.
   We believe your addition will complement the team.
2. To provide what the partner lacks and lack what the partner provides, thus forming part of a whole.
   The flavors of the pepper and garlic complement each other, giving a very rich taste in combination.
   I believe our talents really complement each other.
3. To change a voltage, number, color, etc. to its complement.
4. (obsolete) Old form of compliment