The Complete Lojban Language is a complete description of the artificial language Lojban. It serves as a reference grammar for the language, offering an overview of the language, as well as linguistic details on every aspect of the language. This book serves as the standard defining the language design.

Though this description may sound imposing, technical and formal, the book is written in a light, often humorous style that teaches the reader about the Lojban language, about logic, and about linguistics in general.

Lojban is a version of Loglan, the artificial language project described in the June 1960 Scientific American article of that name. "Loglan" was also referred to by name in Robert Heinlein's classic novel The Moon is a Harsh Mistress, as well as in other novels.

Loglan/Lojban is a language designed for several purposes, including linguistics research (especially involving a proposed test of the Sapir/Whorf hypothesis), foreign language instruction, artificial intelligence research, machine translation and related human/computer interaction applications, and as a stimulating educational and entertaining mental exercise. A few people are interested in Lojban as a prospective international auxiliary language. An international community of aficionados has appeared, writing in and about the language, primarily on the Internet.