I'll take Webster's definition over your interpretation of Church dogma.
The vast majority of Americans, while Christian, are not Catholic.
While I am Catholic, I am also American and live in the popular and limited world, just as Jesus did, and I use the popular and limited definition of my mother tongue.
Definitions that are wide open to interpretation are, for all practical purposes, not definitions at all.
Approximately one in three residents of the US and nearly half of all American Christians are Catholic making it the most populous denomination in the US. The next largest denomination, the Southern Baptists, has only one fourth as many members.