While "tree" is spelled and pronounced similarly, it has a completely different meaning.
You could use "three" itself as a homonym, as it can be used as a noun, adjective, or adverb, depending on the context. For example:
* Noun: "She bought three apples."
* Adjective: "He has three dogs."
* Adverb: "He went to the store three times."
Let me know if you'd like to explore other words that share a similar pronunciation or spelling to "three"!