add is one of the 1000 most common headwords.

Verb

1. (transitive & intransitive) If you add $x$ to $y$, you put $x$ and $y$ together.
Cook for five minutes, then add the remaining spices to the soup.
2. (transitive & intransitive) If you add time, or price, you increase it.
A new kitchen would add value to the home.
We need to add five more waiters by next week.
3. (transitive) If you add something to what you've said, you say something more.
I paused for a moment, then added, "Would you mind if I had some pudding?"

Related words

 Basic math (edit)