what it called when you add ing to a word
-ing -ing is a suffix used to make one of the inflected forms of English verbs. This verb form is used as a present participle, as a gerund, and sometimes as an independent noun or adjective. The suffix is also found in certain words like morning and ceiling, and in names such as Browning.
Addendum In other documents, most importantly in legal contracts, an addendum is an additional document not included in the main part of the contract. It is an ad hoc item, usually compiled and executed after the main document, which contains additional terms, obligations or information. An Additional Agreement to a contract is often an addendum to a contract.