Here are some ways to think about "rudimentary":
* Basic: A rudimentary understanding of a topic means you know the most basic facts but not the more complex details.
* Simple: A rudimentary tool is one that is very simple in design and function.
* Undeveloped: A rudimentary skill is one that is not yet fully developed or refined.
Here are some examples:
* "He had a rudimentary understanding of French." (basic knowledge)
* "The building had only the most rudimentary plumbing." (simple plumbing)
* "Her musical skills were still rudimentary." (not fully developed)
In short, "rudimentary" describes something that is in a basic, simple, or underdeveloped state.