Толковый словарь английского языка Oxford English Reference - add

v.tr. 1 join (one thing to another) as an increase or supplement (add your efforts to mine; add insult to injury). 2 put together (two or more numbers) to find a number denoting their combined value. 3 say in addition (added a remark; added that I was wrong). Phrases and idioms add in include. add-on something added to an existing object or quantity. add to increase; be a further item among (this adds to our difficulties). add up 1 find the total of. 2 (foll. by to) amount to; constitute (adds up to a disaster). 3 colloq. make sense; be understandable. Derivatives added adj. Etymology: ME f. L addere (as AD-, dare put)