Synonyms:
* Confused: This implies a state of being bewildered or disoriented.
* Bewildered: Similar to confused, but with an added sense of being overwhelmed.
* Perplexed: A more formal word, implying difficulty in understanding or solving something.
* Puzzled: Suggests a sense of curiosity or uncertainty.
* Baffled: A strong word that implies being completely unable to understand or solve something.
* At a loss: Describes a state of being unable to act or think.
Antonyms:
* Enlightened: Implies having a clear understanding of something.
* Understanding: Describes a state of comprehending something.
* Informed: Suggests having knowledge or awareness of something.
* Knowledgeable: Implies having a lot of knowledge or expertise.
* Sure: Expresses confidence in something.
* Certain: Indicates a lack of doubt or uncertainty.
The best synonym or antonym for "stumped" will depend on the specific context.