1. <robotics> A mechanical device for performing a task which might otherwise be done by a human, e.g. spraying paint on cars.
See also cybernetics.
2. <chat> An IRC or MUD user who is actually a program. On IRC, typically the robot provides some useful service. Examples are NickServ, which tries to prevent random users from adopting nicks already claimed by others, and MsgServ, which allows one to send asynchronous messages to be delivered when the recipient signs on. Also common are "annoybots", such as KissServ, which perform no useful function except to send cute messages to other people. Service robots are less common on MUDs; but some others, such as the "Julia" robot active in 1990--91, have been remarkably impressive Turing test experiments, able to pass as human for as long as ten or fifteen minutes of conversation.