Meaning of ADDITION in English


əˈdishən, aˈ- noun

( -s )

Etymology: Middle English addicioun, from Middle French addition, from Latin addition-, additio, from additus + -ion, -io -ion


a. : the result of adding : anything added : increase , augmentation

the clerk was a recent addition to the staff

b. : something added that improves or increases value

that table is certainly an addition to the room

2. : the act or process of adding : the joining or uniting of one thing to another

the subject stood in need of correction and addition — Benjamin Farrington

3. obsolete : a designation (as of rank or place of residence) added to a person's name

the names of those justices … with all their additions and titles — William Penn


a. : the process denoted by the sign + of combining two or more numbers so as to obtain their sum

b. : the part of mathematics that treats of addition


a. : a part added to or joined with a building to increase available space

b. : a suburban area marked out into streets and lots as a future residential section

c. additions plural : facilities, structures, equipment, or other property added to what is already in service

6. : direct chemical combination of two or more substances to form a single product

the union of ethylene and chlorine to form ethylene dichloride is an addition reaction: C 2 H 4 +Cl 2 → C 2 H 4 Cl 2

— often contrasted with substitution


a. : the amalgamation in logic of classes or of terms considered with reference to their denotation

the logical addition of “white” and “sweet” results in “either white or sweet (or both)”

b. : alternation 2

8. : a material used in the manufacture of portland cement other than water and untreated calcium sulfate that is interground with the clinker in an amount not exceeding two percent

9. : a dice game played with five dice the object being to achieve the highest numerical total in five or fewer casts

- in addition

- in addition to

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.