1. add-on, addition, improver

a component that is added to something to improve it

Example Sentences:
'the addition of a bathroom was a major improvement'
'the addition of cinnamon improved the flavor'

• add-on
• improver

2. addition

the act of adding one thing to another

Example Sentences:
'the addition of flowers created a pleasing effect'
'the addition of a leap day every four years'

3. addition, gain, increase

a quantity that is added

Example Sentences:
'there was an addition to property taxes this year'
'they recorded the cattle's gain in weight over a period of weeks'

• gain
• increase

4. accession, addition

something added to what you already have

Example Sentences:
'the librarian shelved the new accessions'
'he was a new addition to the staff'

• accession

5. addition

a suburban area laid out in streets and lots for a future residential area

6. addition, plus, summation

the arithmetic operation of summing; calculating the sum of two or more numbers

Example Sentences:
'the summation of four and three gives seven'
'four plus three equals seven'

• plus
• summation