This thesaurus of approximately 10,000 Irish words is divided into three parts: a brief description of how the book may be used an alphabetic index of all the words it contains, and the thesaurus proper. This third section has approximately 500 headwords, again in alphabetical order, and these form the conceptual categories under which all the other words are grouped. A headword can be a noun or a verb or, less frequently, an adjective. Each category or concept is itself broken up into sub-categories which makes for easier handling, more interesting reading, and means the thesaurus is not just a list of words but a system with an organising mind behind it. More than anything else, the book illustrates the amazing wealth of synonym and description available to the Irish speaker and writer and its compilation is a remarkable achievement for only one person.