Are there any offline dictionaries to be used by artificial intelligence (chatbots)?
Here be apples and oranges…. Generally speaking, there are two different components. One is the speech recognition component, and the other is the natural language understanding component. The speech recognition component converts speech into text, and feeds text into the natural language understanding component.
Today, the speech recognition component is considered to be a “solved” problem, and usually relies on open source speech recognition engines (consisting of Acoustic model and Speech corpus), the Google Chrome Speech API, or commercial services such as Nuance.
The natural language understanding component is an “unsolved” problem, which many people are trying to attack in different ways, with varying degrees of success. This success can supposedly be gauged by the well known Turing test; however, since someone allegedly passed that test, Vladimir Veselov with his Eugene Goostman, the academic community has descended into chaos proposing a variety revised tests.
There are lots of “dictionaries”, or ontologies, used for natural language understanding (see Wikipedia Category:Knowledge bases). Wikipedia lists a variety of English Corpora, such as the Spoken English Corpus; however, to my knowledge, spoken language corpora as such are generally not applied to AI. (There is evidence of older research that tried going in that direction.)