Kiwi scientist Michelle Dickinson engaged in a Twitter argument with billionaire Elon Musk on Friday afternoon.
It began when Elon Musk told another user of the site the word 'nano' is "100 percent synonymous with [bullshit]".
This understandably irked Dr Dickinson, who uses the alter ego NanoGirl to teach kids about science.
She took a screenshot of Mr Musk's tweet and told him that nanotech was actually "an integral part of current and future technology".
"Hey @elonmusk we all know that in a world where sensationalism sells, the media world needs a shakeup, but that doesn't happen by calling scientific principles such as the size scale nano 'BS'," the University of Auckland senior lecturer said.
Mr Musk, who made his money with Paypal and currently runs Tesla and SpaceX, told her, "Nano applies to everything & therefore means nothing. Definitely indicates bs. Sorry."
He included a link to the Uncyclopedia definition of nanotechnology, which describes it as a "form of bullshit used by advertisement firms to either make people believe their hair/skin products are magical, or to make investors give funding on the impressions a product will contain magical robots".
Uncyclopedia is a satirical website, and defines 'Elon Musk' as a "self-made egomaniac who wants to send cars into space" who supports "the rehoming of gay orphan transgender puppies".
Dr Dickinson said she actually agreed with Uncyclopedia's definition of nanotechnology, when it applied to advertising gimmicks.
"But that doesn't mean it's BS in the science or engineering world - we don't sell magic products, we use science to create novel solutions."
Social media users appeared to back Dr Dickinson, one pointing out she had a PhD in the subject and he didn't. Another said Mr Musk needs to have a chat with his battery engineers, if he seriously thinks nanotechnology is BS.
Mr Musk is believed to be worth about US$20 billion. Dr Dickinson has had friendlier encounters with other billionaires - she spent a few days on Richard Branson's Necker Island in 2014 to discuss technology and science.
Mr Musk's last tweet on the subject was to say he didn't think a 'grey goo' apocalypse scenario - a swarm of self-replicating nanotech robots that devour everything in their path - was implausible.
Dr Dickinson declined Newshub's request for comment.