* Ibig sabihin (formal, literally means "meaning")
* Kahulugan (formal, literally means "definition")
* Tungkulin (formal, literally means "function" but can be used for "define" in some contexts)
* Tukuyin (more active, literally means "determine" but can be used for "define")
The best translation depends on the context.
Here are some examples:
* Can you define what a noun is?
* Maaari mo bang tukuyin kung ano ang pangngalan?
* Ano ang ibig sabihin ng pangngalan?
* The purpose of this document is to define the company's goals.
* Ang layunin ng dokumentong ito ay tukuyin ang mga layunin ng kumpanya.
* Ang tungkulin ng dokumentong ito ay tukuyin ang mga layunin ng kumpanya.
Remember that context is key when translating. If you provide more context about how you want to use the word "define," I can give you a more accurate translation.