Simple and direct:
* The dancer's movements were marked by incredible fluidity.
* The conversation flowed with a natural fluidity.
Descriptive:
* The artist's brushstrokes conveyed a sense of fluidity and movement.
* The river's current flowed with a smooth, irresistible fluidity.
Figurative:
* The transition between the two scenes was marked by a fluidity of time and space.
* Her writing style is characterized by its fluidity and clarity.
Specific:
* The fluidity of the market is making it difficult to predict future trends.
* The fluidity of the language makes it easy to learn.
With other parts of speech:
* The fluidity of the situation made it hard to plan.
* He spoke with a fluidity that made him seem confident and knowledgeable.
* The lack of fluidity in the system made it difficult to navigate.
Remember, the best way to use "fluidity" depends on the context and the meaning you want to convey.