To abbreviate means to shorten a word or phrase by leaving out some of its letters. When you write “Dr.” instead of “Doctor” or “Ave.” instead of “Avenue,” you're abbreviating. The shortened form is called an abbreviation.

People abbreviate to save time and space. Instead of writing out “Mister Benjamin Franklin” every time, you can write “Mr. Benjamin Franklin.” States have official abbreviations: California becomes CA, Massachusetts becomes MA. Days of the week get abbreviated too: Monday becomes Mon., Thursday becomes Thu.

Some abbreviations become so common that people forget the original words. When you see “etc.” at the end of a list, it's short for the Latin phrase et cetera, meaning “and other things.” The word “okay” may have come from abbreviating a joking spelling of “all correct” as “O.K.” or “OK.”

Scientists and businesses use abbreviations constantly. NASA stands for National Aeronautics and Space Administration. DNA stands for deoxyribonucleic acid. Can you imagine writing out deoxyribonucleic acid every single time?

When you abbreviate thoughtfully, you make writing clearer and faster to read. But abbreviate too much, and your writing becomes a confusing jumble of letters that nobody can understand.