Trump says he's never heard of the term 'second lady'

While hosting a picnic for military families on the South Lawn of the White House, Donald Trump addressed the crowd to pledge his "unwavering support for military families."

He recognized Vice President Mike Pence's son, who is in the Marines, but it was his comment about Pence's wife that raised eyebrows.

While reading his prepared remarks, Trump stopped to note that he has never heard the term "second lady" before.

Here's his statement, according to New York Magazine:

There is one military family here I am especially excited to recognize. Our great Vice-President Mike Pence and our second lady — never heard that term before but that's what they say, and she is some lady, that I can tell you — of the United States, Karen Pence, are here along with their son Maine First Lieutenant Michael Pence.

The term "first lady" was coined 1849. A few decades later, Jennie Tuttle Hobart, the wife of President William McKinley's vice-president, Garret Hobart, called herself the "second lady," making the title official.

Though former Vice President Joe Biden's wife was more often called Dr. Jill Biden than the second lady, it's certainly not a rare term -- the White House website calls Karen Pence "Second Lady of the United States," and she used the moniker as her Twitter handle.

See photos of the vice president and second lady: