Gforth Manual - Full GNU Forth manual, linked Table of Contents. On website of one of Gforth developers. - http://www.complang.tuwien.ac.at/forth/gforth/Docs-html/
Gforth: GNU Forth - Free, fast, portable implementation of ANS Forth, on GNU website. Works well with Emacs editor. Many nice features: input completion and history, powerful locals facility, object oriented aspects. Employs traditional implementation methods: inner interpre - http://www.jwdt.com/~paysan/gforth.html