in the vernacular

Samuel Wilson was well-known for his fair business practices and jovial personality, so the townspeople referred to him as Uncle Sam. Eventually, his fair-dealing reputation won him a military contract to provide beef and pork to the soldiers quartered near Troy during the War of 1812. In order to distinguish the supplies designated for the troops, Wilson stamped a large "U.S." to stand for United States on the barrels of meat, even this abbreviation was not yet in the vernacular.

There are a number of different definitions of "vernacular" in my dictionary, and my take is that it refers to "daily English." Correct me if I am wrong. Thanks.