We cannot have a chatbot glossary without the definition of a chatbot of course!
Since the definition of a chatbot is fairly broad, let us start with what Wikipedia says: “A chatbot (also known as a talkbot, chatterbot, Bot, chatterbox, Artificial Conversational Entity) is a computer program which conducts a conversation via auditory or textual methods.”
I actually like this definition even if it sounds a little technical, simply because it captures all the important aspects of a chatbot without being too long. Chatbots are actually used to conduct conversation via both auditory methods (e.g. Alexa) and textual methods (e.g. Mitsuku).