Pronunciation: (ad),[key] —v.t. 1. to unite or join so as to increase the number, quantity, size, or importance: to add two cups of sugar; to add a postscript to her letter; to add insult to injury. 2. to find the sum of (often fol. by up): Add this column of figures. Add up the grocery bills. 3. to say or write further.
4. to include (usually fol. by in): Don't forget to add in the tip.
—v.i. 1. to perform the arithmetic operation of addition: children learning to add and subtract. 2. to be or serve as an addition (usually fol. by to): His illness added to the family's troubles. 3. add up, a. to make the desired, expected, or correct total: These figures don't add up right. b. to seem reasonable or consistent; be in harmony or accord: Some aspects of the story didn't add up. 4. add up to, to signify; indicate: The evidence adds up to a case of murder.