The short written form of Wyoming, one of the American states. You will only meet this in writing, where space is tight — on an address label, in a table of state names, in an old book, on a form. Nobody says "Wyo." out loud; you read it and then say "Wyoming" in your head. The dot at the end is what tells you it is a shortened word, not a word of its own. These old-style state abbreviations were the normal way to write states before the postal service brought in the two-letter codes in 1963. Today the post office wants WY (two capital letters, no dot), and that is what you will see on modern mail. So Wyo. now feels a bit old-fashioned — you meet it in books, newspapers, footnotes, historical writing, and sometimes in the names of local businesses. Both forms are still perfectly understandable to any American.