Addition

Ad·di·tion

Addition

n.
  1. The act of adding two or more things together; -- opposed to subtraction or diminution.
  2. Anything added; increase; augmentation; as, a piazza is an addition to a building.
  3. That part of arithmetic which treats of adding numbers. (Math.)
  4. A dot at the right side of a note as an indication that its sound is to be lengthened one half. (Mus.) [R.]
  5. A title annexed to a man's name, to identify him more precisely; as, John Doe, Esq.; Richard Roe, Gent.; Robert Dale, Mason; Thomas Way, of New York; a mark of distinction; a title. (Law)
  6. Something added to a coat of arms, as a mark of honor; -- opposed to abatement. (Her.)

Phrases & Compounds
Vector addition
that kind of addition of two lines, or vectors, AB and BC, by which their sum is regarded as the line, or vector, AC.