Here are some other ways to say it depending on context:
* "3ème année" - This is a shorthand version of "troisième année" often used in academic contexts.
* "année de troisième" - This is a more formal way of saying "third year" and specifically refers to the third year of secondary school in France.
* "troisième année d'études" - This phrase literally translates to "third year of studies" and can be used in various contexts.
The best translation will depend on the specific situation you are in.