Here's what Wikipedia thinks:
A robot is a mechanical or virtual, artificial agent. It is usually a system, which, by its appearance or movements, conveys a sense that it has intent or agency of its own. The word robot can refer to both physical robots and virtual software agents, but the latter are usually referred to as bots to differentiate.
While there is still discussion about which machines qualify as robots, a typical robot will have several, though not necessarily all of the following properties:
1 is not 'natural' i.e. artificially created
2 can sense its environment, and manipulate or interact with things in it
3 has some ability to make choices based on the environment, often using automatic control or a preprogrammed sequence
4 is programmable
5 moves with one or more axes of rotation or translation
6 makes dexterous coordinated movements
7 appears to have intent or agency
Quite a precise definition, yet I would argue that it does not settle the question.
Over the next few days I'll post a few examples below. Looking forward to your additions!