General uncertainty:
* Ambiguous: This is the most direct and neutral term, simply indicating that the meaning is unclear.
* Uncertain: A more general term for doubt or lack of confidence.
* Vague: Suggests a lack of clarity or precision.
* Indefinite: Similar to vague, but implies a lack of specific boundaries.
* Dubious: Implies a suspicion or skepticism about the meaning.
More specific to the meaning of a word:
* Equivocal: Suggests that the word has two or more possible meanings, making it difficult to interpret.
* Ambiguous: Can also be used in this context, highlighting the multiple possible interpretations.
* Unclear: A straightforward way to say that the meaning is not clear.
* Fuzzy: Suggests a lack of sharpness or precision in the meaning.
Related to the speaker's own understanding:
* Unsure: This focuses on the speaker's own lack of understanding.
* Confused: Indicates a state of mental muddle about the meaning.
* Puzzled: Implies a feeling of perplexity or bewilderment.
* Bewildered: Stronger than puzzled, suggesting a sense of disorientation or disarray.
The best word to use will depend on the specific context and the level of uncertainty you want to convey.