Symbol Grounding Problem
The problem of how words (symbols) get their meanings, and hence to the problem of what meaning itself really is.
Origin
Stevan Harnad, a Hungarian-born Canadian cognitive scientist, posed the problem in his 1990 paper "The Symbol Grounding Problem" in Physica D. Harnad asked how symbols in a formal system can ever acquire meaning if they are only defined in terms of other symbols — how to "get off the symbol/symbol merry-go-round." The work was directly inspired by John Searle's 1980 Chinese Room Argument, which demonstrated that syntactic manipulation alone does not produce semantic understanding.
Everyday Use
Imagine looking up a word in a foreign-language dictionary where every definition uses only other foreign words — you'd go in circles, never grasping meaning. That's the symbol grounding problem: at some point, symbols need to connect to real-world experience, not just to other symbols. It's why chatbots can string together coherent sentences without necessarily "understanding" what they're saying.