Formal:
* Responded: This is a more neutral and formal alternative to "replied".
* Answered: This implies that the speaker was giving a direct answer to a question.
* Retorted: This implies a sharp or witty response, often in disagreement.
* Rejoined: This implies a continuation of a conversation or argument.
Informal:
* Said: A more casual and direct alternative to "replied".
* Chimed in: This implies joining a conversation.
* Shot back: This suggests a quick and sharp response, often in defense.
* Fired back: This implies a strong and forceful response.
* Countered: This implies a response that contradicts the previous statement.
Other options:
* Explained: This implies a detailed and informative response.
* Elaborated: This implies adding more detail to a previous statement.
* Clarified: This implies providing further explanation to make something clearer.
Examples:
* Instead of: "She replied, 'I don't know.'"
* You could say: "She responded, 'I don't know.'" (Formal)
* Or: "She said, 'I don't know.'" (Informal)
Ultimately, the best word to use will depend on the specific context and desired tone of your writing.