An abbreviation is a shortened form of a word or phrase. Here are some examples:
* Dr. for Doctor
* Mr. for Mister
* Mrs. for Mistress
* St. for Street
* USA for United States of America
Other types of shortened words:
* Acronyms: Words formed from the first letters of a phrase, like NATO (North Atlantic Treaty Organization).
* Contractions: Combining two words into one by omitting letters, like don't (do not) or can't (cannot).
* Clipping: Shortening a word by removing part of it, like phone (telephone) or fridge (refrigerator).
Let me know if you'd like examples of a specific type of shortened word!