Addition definition

(1) The act of adding one thing to another

"The addition of flowers created a pleasing effect"

"The addition of a leap day every four years"

(2) The arithmetic operation of summing; calculating the sum of two or more numbers

"The summation of four and three gives seven"

"Four plus three equals seven"

(3) A component that is added to something to improve it

"The addition of a bathroom was a major improvement"

"The addition of cinnamon improved the flavor"

(4) A suburban area laid out in streets and lots for a future residential area

(5) Something added to what you already have

"The librarian shelved the new accessions"

"He was a new addition to the staff"

(6) A quantity that is added

"There was an addition to property taxes this year"

"They recorded the cattle's gain in weight over a period of weeks"