If you're thinking of "phonetic" as relating to the sounds of speech:
* Non-phonetic: This is the most direct opposite, meaning not related to sounds of speech.
* Semantic: This focuses on the meaning of words rather than their sounds.
* Visual: This refers to written representation rather than spoken sounds.
* Grammatical: This focuses on the structure of language rather than its sounds.
If you're thinking of "phonetic" as meaning "written according to pronunciation":
* Orthographic: This refers to the standard spelling of words.
* Etymological: This focuses on the historical origin of words.
Ultimately, the best opposite will depend on the specific context in which you're using "phonetic".