If you're thinking about the act of responding to someone:
* Ignored: This is the most direct opposite, meaning to completely disregard the other person's communication.
* Refused: This implies a deliberate decision not to respond, often with a negative connotation.
* Disregarded: This is similar to ignored, but it emphasizes a lack of attention or consideration.
* Overlooked: This implies that the communication was not noticed or acknowledged.
If you're thinking about the content of the response:
* Disagreed: This means to express an opposing opinion.
* Contradicted: This means to directly state the opposite of what was said.
* Denied: This means to refuse to acknowledge the truth of a statement.
Other possible opposites:
* Started: If "replied" means to continue a conversation, then "started" could be considered an opposite.
* Asked: If "replied" refers to providing an answer, then "asked" could be considered an opposite.
Ultimately, the best opposite for "replied" depends on the specific situation and meaning you want to convey.