noun British Archaic.
a male native or resident of the United States.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Word Origin and History for brother jonathan
sobriquet for "United States," 1816, often connected with Jonathan Trumbull (1740-1809) of Connecticut, called Brother Jonathan by George Washington, who often sought his advice, somehow in reference to 2 Sam i:26.
Online Etymology Dictionary, © 2010 Douglas Harper