Error description Thrown if the parser encounters a token which does not name a word in the current vocabulary search path. If any words with this name exist in vocabularies not part of the search path, a number of restarts will offer to add those vocabularies to the search path and use the chosen word.
Notes Apart from a missing USE:, this error can also indicate an ordering issue. In Factor, words must be defined before they can be called. Mutual recursion can be implemented via DEFER:.