Donald Trump's got his pronouns all mixed up ... getting onstage during a rally and calling Latin singer Nicky Jam a "hot" woman -- and, looking a bit surprised to find he's actually a dude!

The 45th POTUS had a rally in Las Vegas Friday night ... and he introduced Nicky to the crowd -- asking fans if they know Nicky and adding "she's hot."

Trump then asks where Nicky's at ... and, watch the video -- once he catches a glimpse of NJ, he looks a bit surprised to see a guy walking toward him.

To his credit, Jam rolls with the error ... moving on quickly and putting his full support behind DJT while onstage -- a pretty masterful recovery.

Unclear if Trump meant hot as in looks or hot as in popular when discussing Nicky ... but, either way, fans are pointing out he didn't seem totally sure about who Nicky was.

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Jam posted about the viral moment on Instagram BTW ... sharing a pic with Trump's words written along the bottom -- and puttiing a ton of laughing emojis in the caption.

Jam's a big deal in Latin music ... having won multiple Latin Grammys, Billboard Awards and more. His song, "X," has more than 1 billion listens on Spotifty -- so, this is a pretty big endorsement for Trump.

The endorsement comes after a week Donald Trump feels he just dominated ... saying multiple times he feels he won the debate over Kamala Harris on Tuesday -- and insisting he won't debate her again.

Worth noting ... Donald Trump has said he doesn't ascribe to pronouns -- and, when it comes to Nicky, he's defintely living up to the statement.