What is AI Winter? The pages here about LispLanguage always say that Lisp people have (to quote) "a hangover from AI Winter". What was there? [Note 1]
A term coined by RichardGabriel for the (circa 1990-94?) crash of the wave of enthusiasm for Lisp and AI, following a boom in the 1980s.
A specific case of HypeWinter? - what happens to a good idea when it's hyped beyond all recognition, after the hype.
In other words, the dot-com bubble equivalent for AI.
Quoting a UseNet post to comp.lang.lisp from DuaneRettig?:
LispLanguage was always very general-purpose, but was especially good at ArtificialIntelligence, and was for a long time very closely associated with AI. The Lisp companies rode the great AI wave in the early 80's, when large corporations poured billions of dollars into the AI hype that promised thinking machines in 10 years. When the promises turned out to be harder than originally thought, the AI wave crashed, and Lisp crashed with it because of its association with AI. We refer to it as the AI Winter. Some high-level managers who were burned by the AI hype actually kill any project with either the name AI or Lisp in it (that's why you don't even see or hear the term AI much anymore; most of the more successful branches of AI (e.g. speech recognition, expert systems) have distanced themselves from the name. And many distanced themselves from Lisp as well, trying to make a go of their projects in C, C++, or Java. Some have succeeded. Others, not. Some have come back to Lisp, and not told anyone, for the twofold reason that it might be a negative in their marketing strategy to mention the L word, and also because it became a competitive advantage to not mention how their time-to-market is so quick.
If you really want to know and want to read some first-hand experiences, search for the following threads on UseNet: