addition

noun

1. The act of adding anything.
2. Anything that is added.
3. The arithmetic operation of adding.
4. A dot at the right side of a note as an indication that its sound is to be lengthened one half.
5. A title annexed to a person's name to identify him or her more precisely.
6. Something added to a coat of arms, as a mark of honour.
7. an organic reaction where two or more molecules combine to form a larger one (the adduct).