If you describe someone as an all-American boy or girl, you mean that they seem to have all the typical qualities that are valued by ordinary Americans, such as good looks and love of their country.
...the image of the standard all-American boy.
all-American in British English
adjective US
1.
representative of the whole of the United States
2.
composed exclusively of American members
3.
(of a person) typically American
the company looks for all-American clean-cut college students
all-American in American English
(ˌɔləˈmɛrɪkən)
US
adjective
1.
made up entirely of Americans or American parts
2.
representative of the U.S. as a whole, or chosen as the best in the U.S.
3.
of all the Americas
noun
4.
a hypothetical football team or other team made up of college players voted the best of the year in the U.S.
5.
a player chosen for such a team
Examples of 'all-American' in a sentence
all-American
He had fine features and an all-American corn-fed glow, getting slightly older, on him.