1. To reply or respond to; SYN. reply, respond.
2. To give the correct answer or solution to.
3. To give a defence or refutation of (a charge) or in (an argument).
4. To be satisfactory for; meet the requirements of or serve the purpose of.
5. To be liable or accountable.
6. To match or correspond.
7. To react to a stimulus or command.
8. To respond to a signal.