Cassandra, who lives in Pittsburgh, Pennsylvania, wonders about the rules for how to punctuate titles such as Professor and Doctor. Growing up in South Africa, she was taught that, in contrast to practice in the United States, the titles Dr, Mr, and Mrs are not followed by a period because they stand for the whole words Doctor, Mister, and Mistress and include the first and last letters of each term. In contrast, she says, she was told that Prof should be followed by a period because it’s an abbreviation of the word Professor, cutting the word off in the middle. When it comes to abbreviations, there are lots of exceptions to punctuation rules. In the United States, for example, people sometimes leave out the period in US, UN, and CEO when using shortened forms of United States, United Nations, and Chief Executive Officer.
This is part of a complete episode.