Directly from "leon":
* leonine: (adj.) resembling a lion, especially in its mane or roar.
* leonid: (n.) a member of a group of meteors that appear to radiate from the constellation Leo.
With other prefixes or suffixes:
* leontopodium: (n.) a genus of flowering plants, also known as "edelweiss," with woolly, white, star-shaped flower heads that resemble a lion's paw.
* leontopetalum: (n.) a genus of flowering plants with petals that resemble a lion's claw.
* leontiasis: (n.) an abnormal enlargement of the bones of the face, giving it a lion-like appearance.
* leonine: (adj.) pertaining to lions, especially in its mane, roar, or strength.
* leontiasis ossea: (n.) a rare condition characterized by the overgrowth of bone tissue in the face, particularly in the jaw and cheekbones, giving the patient a lion-like appearance.
In other languages:
* Lion: (English)
* Löwe: (German)
* León: (Spanish)
* Lione: (Italian)
* Lion: (French)
These are just a few examples, and there are many other words that use the root "leon" in various contexts.