The suspended fluid reminded Langdon of a video he had once seen of a water droplet in zero G. Although he knew the globule was microscopic, he could see every changing gorge and undulation as the ball of plasma rolled slowly in suspension.
There are no more uses of "undulate" in the book.
Show samples from other sources
A sidewinding snake uses less energy to cover the same distance as a laterally undulating snake uses.
The dancers’ arms undulated in unison to add to the ethereal effect.