n. [ Cf. OF. couplement. ] Union; combination; a coupling; a pair. [ Obs. ] Shak. [ 1913 Webster ]

And forth together rode, a goodly couplement. Spenser. [ 1913 Webster ]

n. [ L. complementun: cf. F. complément. See Complete, v. t., and cf. Compliment. ] 1. That which fills up or completes; the quantity or number required to fill a thing or make it complete. [ 1913 Webster ]

2. That which is required to supply a deficiency, or to complete a symmetrical whole. [ 1913 Webster ]

History is the complement of poetry. Sir J. Stephen. [ 1913 Webster ]

3. Full quantity, number, or amount; a complete set; completeness. [ 1913 Webster ]

To exceed his complement and number appointed him which was one hundred and twenty persons. Hakluyt. [ 1913 Webster ]

4. (Math.) A second quantity added to a given quantity to make it equal to a third given quantity. [ 1913 Webster ]

5. Something added for ornamentation; an accessory. [ Obs. ] [ 1913 Webster ]

Without vain art or curious complements. Spenser. [ 1913 Webster ]

6. (Naut.) The whole working force of a vessel. [ 1913 Webster ]

7. (Mus.) The interval wanting to complete the octave; -- the fourth is the complement of the fifth, the sixth of the third. [ 1913 Webster ]

8. A compliment. [ Obs. ] Shak. [ 1913 Webster ]

Arithmetical compliment of a logarithm. See under Logarithm. --
Arithmetical complement of a number (Math.), the difference between that number and the next higher power of 10; as, 4 is the complement of 6, and 16 of 84. --
Complement of an arc or
Complement of an angle (Geom.), the difference between that arc or angle and 90°. --
Complement of a parallelogram. (Math.) See Gnomon. --
In her complement (Her.), said of the moon when represented as full. [ 1913 Webster ]

v. t. 1. To supply a lack; to supplement. [ R. ] [ 1913 Webster ]

2. To compliment. [ Obs. ] Jer. Taylor. [ 1913 Webster ]

a. 1. Supplying, or tending to supply, a deficiency; fully completing. “Complemental ceremony.” Prynne. [ 1913 Webster ]

2. Complimentary; courteous. [ Obs. ] Shak. [ 1913 Webster ]

Complemental air (Physiol.), the air (averaging 100 cubic inches) which can be drawn into the lungs in addition to the tidal air, by the deepest possible inspiration. --
Complemental males (Zool.), peculiar small males living parasitically on the ordinary hermaphrodite individuals of certain barnacles. [ 1913 Webster ]

a. Serving to fill out or to complete; as, complementary numbers. [ 1913 Webster ]

Complementary colors. See under Color. --
Complementary angles (Math.), two angles whose sum is 90°. [ 1913 Webster ]

n. [ See Complimentary. ] One skilled in compliments. [ Obs. ] B. Jonson. [ 1913 Webster ]

n. (Linguistics) the grammatical relation of a word or phrase to a predicate. [ WordNet 1.5 ]