Hillary Clinton Laughs at Trump's 'Gulf of America' Plan at Inauguration

Hillary Clinton couldn't keep her composure during Donald Trump's 2nd inaugural address ... openly laughing at the president following his "Gulf of America" announcement.

Check it out ... as Trump -- who had just been sworn in as the United States' 47th president -- reiterated his plan to rename the Gulf of Mexico to the "Gulf of America," HC burst out laughing ... and prompted a bit of side eye from her husband, former President Bill Clinton.

The former Secretary of State did try to stifle her laughter ... watch the video, you can see her bury her chin in her chest as Trump continued to address the nation.

While many of the inauguration attendees inside the Capitol Building responded to Trump's declaration with a standing ovation  ... 47's political rivals -- including President Joe Biden, Vice President Kamala Harris, as well as the Clintons -- notably stayed seated.

All 4 of the politicians have been vocal critics of Trump ... who defeated Hillary in the 2016 presidential election and Kamala this past November.

Trump first announced his plan to rename the Gulf of Mexico earlier this month, when he told reporters at a Mar-a-Lago press conference that the "Gulf of America" had "a beautiful ring."

At the time, he declared it was an "appropriate" rebrand given the amount of work the U.S. does in the territory.

However, Mexican President Claudia Sheinbaum hit back at Trump's plan ... suggesting they rename North America to "Mexican America," which the region had once been called in the 1810s.