A good Catholic Dictionary is a reference book indispensible to every Catholic Home School. The Catholic  Faith has a vocabulary much of which is specific to the Church and which is essential to the understanding of its teaching.  Among Father John Hardon's many works his Modern Catholic Dictionary is popular not only for its definitions but also for its lucid explanations of things Catholic. It is available in both hard cover and paperback editions as well as an abridged pocket-book edition.  Donald Attwater's A Catholic Dictionary  is a reprint of the best known pre-Vatican II Catholic dictionary in English. Another good pocket book is Father Peter Stravinskas' The Catholic Dictionary.