'Complement of an angle' definitions:

Definition of 'Complement of an angle'

From: GCIDE

Complement \Com"ple*ment\, n. [L. complementun: cf. F. compl['e]ment. 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[deg].
Complement of a parallelogram. (Math.) See Gnomon.
In her complement (Her.), said of the moon when represented as full. [1913 Webster]